Design of Power Plant for House

Power Plant Engineering

Electrical Engineeering

University of Engineering and technology,

Lahore

Mudasser rahim2013-EE-36

January 15th, 2017


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Acknowledgement

I am grateful to the well known Dr. prof. Imran Shiekh whose guidence helpedme a lot in making of this report. I have learned different steps and techniques

with the help of slides he provided to me. These things helped me in making myassignment succesful. May Allah always bless him for the support he always

provide us during the study of the course.

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Abstract

Everyday electricity plays a key role in keeping our homes and businesses to runsmoothly. It allows people to do work at school and other places, and suppliesenergy to appliances in all sectors but as our non-renewable sources are declining,the price of electricity is increasing. As our non-renewable resources are set to de-cline further in the years to come, it is important for us to move towards renewablesources of energy like wind, hydro power, biomass and tidal. In this report ourmain purpose is to move from non-renewable source of energy to renewable likesolar energy. Solar energy i.e. energy from the sun provide consistent and steadysource of solar power throughout the year. The main benefit of solar energy isthat it can be easily deployed by both home and business users as it does notrequire any huge set up like in case of wind or geothermal power. Solar energynot only benefits individual owners, but also benefit environment as well. So weare converting our load to solar energy.

Contents

1 Background 11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Total Load Calculation . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Map of Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Heating and Cooling of Building 32.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.2 Average Outdoor Temprature . . . . . . . . . . . . . . . . . . . . . 32.3 Design Conditions for Heating and Cooling of Building . . . . . . . 4

2.3.1 Heating or Cooling load . . . . . . . . . . . . . . . . . . . . 52.3.2 Wind Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.3.3 Moisture Level . . . . . . . . . . . . . . . . . . . . . . . . . 62.3.4 Solar Radiation . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.4 SOLAR AIR TEMPRATURE . . . . . . . . . . . . . . . . . . . . . 82.4.1 Effect of Solar Heated Walls on Design Heat Load . . . . . . 8

3 Heat Gain from People, Lights and Equipments 103.1 PEOPLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103.2 LIGHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113.3 EQUIPMENTS and APPLIANCES . . . . . . . . . . . . . . . . . . 12

3.3.1 USEFUL ENERGY CONSUMPTION . . . . . . . . . . . . 13

4 Heat Loss due to Appliances 144.1 FANS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144.2 Air Conditioner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144.3 Electric Heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144.4 Energy Savers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.5 Smart TV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.6 Desktop computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.7 Electric Kettle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.8 FRIDGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.9 Electric Iron . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164.10 Microwave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164.11 Table Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164.12 Toaster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164.13 Exhaust Fans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

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4.14 Washing Machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164.15 Water Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164.16 Charging Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.17 Printer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.18 Laptop Computers . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.19 Exhaust Hood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5 Solar Power Generation 185.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5.1.1 Thermal Systems . . . . . . . . . . . . . . . . . . . . . . . . 185.1.2 Photovoltaic Systems . . . . . . . . . . . . . . . . . . . . . . 18

5.2 Solar Collectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185.2.1 Concentrators . . . . . . . . . . . . . . . . . . . . . . . . . . 18

6 Production of Electricity through Sunlight 216.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216.2 Thermal Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

6.2.1 Large Scale production . . . . . . . . . . . . . . . . . . . . . 216.2.2 Small Scale production . . . . . . . . . . . . . . . . . . . . . 22

7 Heating from Solar Power 247.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247.2 Solar Water Heating . . . . . . . . . . . . . . . . . . . . . . . . . . 24

7.2.1 Active Solar Water Heating System . . . . . . . . . . . . . . 247.3 Storage Tanks And Solar Collectors . . . . . . . . . . . . . . . . . . 25

7.3.1 Flat Plate Collector . . . . . . . . . . . . . . . . . . . . . . . 257.3.2 Integral collector-storage systems . . . . . . . . . . . . . . . 267.3.3 Evacuated-tube solar collectors . . . . . . . . . . . . . . . . 26

7.4 Room Air Heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267.4.1 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . 26

7.5 Installing The System . . . . . . . . . . . . . . . . . . . . . . . . . 267.6 Calculation of Heat Energy from Hot Water . . . . . . . . . . . . . 27

8 Cooling From Solar power 288.1 Flat Plate Collector . . . . . . . . . . . . . . . . . . . . . . . . . . . 288.2 Desiccant cooling system . . . . . . . . . . . . . . . . . . . . . . . . 28

9 Design of System 309.1 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

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List of Figures

1.1 House Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2.1 Average Temprature per month . . . . . . . . . . . . . . . . . 32.2 Tebular form of Average Temprature . . . . . . . . . . . . . 42.3 Dry bulb temperature lines on a psychrometric chart . . . . 62.4 Wet bulb temperature lines on a psychrometric chart . . . . 72.5 Comfort zone in a psychrometric chart . . . . . . . . . . . . . 7

3.1 Heat Gain from People in Conditional Space . . . . . . . . . 11

5.1 Parabolic trough . . . . . . . . . . . . . . . . . . . . . . . . . . . 195.2 Power Tower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195.3 Heliostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205.4 parabolic dish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

6.1 Large scale production . . . . . . . . . . . . . . . . . . . . . . . 226.2 Photovoltaic System . . . . . . . . . . . . . . . . . . . . . . . . . 226.3 Voltaic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236.4 Solar Stirling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

7.1 Active Solar Water Heating . . . . . . . . . . . . . . . . . . . . 257.2 Open loop Water Heating . . . . . . . . . . . . . . . . . . . . . 27

9.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

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Chapter 1

Background

1.1 Introduction

The house is located in Gulshan Iqbal, Rahim Yar khan. It is located in southernPunjab. The city geographical coordinates are 28 25’ 0” North, 70 18’ 0” East.It is a double story building having 6 bed rooms 2 kitchen and 5 washrooms. Itstotal area is 3321.51ft2. Three people are living in the house.

1.2 Total Load Calculation

The Electrical base load of the house is 17.87kW, which include the followingequipments.

Equipment Load Yearly hours

1. Air conditioner 2x2500W = 5000W. 1080 hrs2. Electric heater 1x2000W = 2000W. 100 hrs3. Energy Savers 50x25W = 1250W. 1500 hrs4. Smart Tv 1x75W = 75 W. 1800 hrs5. Ceiling fans 15x75W = 1125W. 1600 hrs6. Desktop Computer 1x200W = 200W. 500 hrs7. Electric Kettle 1x1200W = 1200W. 50 hrs8. Fridge 2x200W = 400W. 8000 hrs9. Electric Iron 1x1000W =1000W. 300 hrs10. Microwave 1x2000W =2000W. 150 hrs11. Table Fan 1x100W =100W. 100 hrs12. Toaster 1x1000W =1000W. 20 hrs13. Washing Machine 1x500W =500W. 100 hrs14. Water pump 1x2000W =2000W. 1000 hrs15. Charging devices 4x5W = 20W. 5000 hrs16. Exhaust Fans 2x200W=400W. 6000hrs17. Printer 1x100W=100W. 1000hrs18. Laptop Computer 2x50W=100W. 6000hrs19. Exhaust Hood 1x150W=150W. 4000hrs

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Total Base Load= 18.62kW

According to formula for energy calculation

Energy= (Power in kW) x (number of hours)

Total consumption will be 6,500kWh/year

1.3 Map of Building

The house is 3321 sq. feet and having double story, its map of both stories areshown here:

Figure 1.1: House Map

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Chapter 2

Heating and Cooling of Building

2.1 Introduction

Heating and cooling of building is needed to provide thermal comfort and accept-able indoor air quality for the residents. Heating can be accomplished by heatingthe air with in the space or heating the occupants directly by radiation. Coolingis of two types sensible and latent cooling. Sensible cooling involves the controlof air temprature while latent cooling involves the control of air humidity.

2.2 Average Outdoor Temprature

We don’t know what will be the weather in future. Therefore, we turn to the pastinstead of the future and bet that the past weather data averaged over severalyears will be representative of a typical year in the future.

Figure 2.1: Average Temprature per month

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The average temprature during differnt month of the year in tebular form isgiven as follows:

Figure 2.2: Tebular form of Average Temprature

The temperature normals are measured in the period 1985 to 2015.Source:WMO (World Meteorological Organization)

For ordinary building we are designing that the economics and comfort meet atthe 97.5 percent level in winter. That is, the heating system will provide thermalcomfort 97.5 percent of the time but may fail to do so during 2.5 percent of thetime. For example the 97.5 percent winter design temperature for Rahim Yarkhan is 6oC, and thus the temperatures in Rahim Yar Khan may fall below 6oCabout 2.5 percent of the time during winter months in a typical year.

The winter percentages are based on the weather data for the months ofDecember, January, and February. The three winter months have a total of31+31+28=90 days and thus 2160 hours. Therefore, the conditions of a housewhose heating system is based on the 97.5 percent level may fall below the com-fort level for 2160x2.5%=54 hours during the heating season of a typical year.Most people will not even notice it because everything in the house will startgiving off heat as soon as the temperature drops below the thermostat setting.The minimum temperatures usually occur between 6:00 AM and 8:00 AM so-lar time.While the Summer percentages are based on the four months Junethrough September The maximum temperatures usually occur between 2:00 PMand 4:00 PM solar time.

2.3 Design Conditions for Heating and Cooling

of Building

The size of a heating or cooling system for a building is determined on the basisof the desired indoor conditions that must be maintained based on the outdoorconditions that exist at that location. The desirable ranges of temperatures, hu-midity, and ventilation rates (the thermal comfort zone) constitute the typical

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indoor design conditions, and they remain fairly constant. For example, the rec-ommended indoor temperature for general comfort heating is 22o. The outdoorconditions at a location, on the other hand, vary greatly from year to year, monthto month, and even hour to hour. The set of extreme outdoor conditions underwhich a heating or cooling system must be able to maintain a building at theindoor design conditions is called the outdoor design conditions.

When designing a heating, ventilating, and air-conditioning (HVAC) system,perhaps the first thought that comes to my mind is to select a system that islarge enough to keep the indoors at the desired conditions at all times even underthe worst weather conditions. But sizing an HVAC system on the basis of themost extreme weather on record is not practical since such an oversized systemwill have a higher initial cost, will occupy more space, and will probably have ahigher operating cost because the equipment in this case will run at partial loadmost of time and thus at a lower efficiency. We would not mind experiencingan occasional slight discomfort under extreme weather conditions if it means asignificant reduction in the initial and operating costs of the heating or coolingsystem. But I will try to make a good compromise between economics and comfort.

2.3.1 Heating or Cooling load

The heating or cooling loads of a building represent the heat that must besupplied to or removed from the interior of a building to maintain it at the desiredconditions. A distinction should be made between the design load and the actualload of heating or cooling systems. The design (or peak) heating load is usuallydetermined with a steady-state analysis using the design conditions for the indoorsand the outdoors for the purpose of sizing the heating system . This ensures thatthe system has the required capacity to perform adequately at the anticipatedworst conditions. But the energy use of building during a heating or coolingseason is determined on the basis of the actual heating or cooling load, whichvaries throughout the day.

The internal heat load (the heat dissipated off by people, lights, and appli-ances in a building) is usually not considered in the determination of the designheating load but is considered in the determination of the design cooling load.This is to ensure that the heating system selected can heat the building evenwhen there is no contribution from people or appliances, and the cooling systemis capable of cooling it even when the heat given off by people and appliances isat its highest level.

2.3.2 Wind Speed

Wind increases heat transfer to or from the walls, roof, and windows of a buildingby increasing the convection heat transfer coefficient and also increasing the infil-tration. Therefore, wind speed is another consideration when determining theheating and cooling loads. The average values of wind speed to be considered are6 km/h for winter and 18 km/h for summer.

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The corresponding design values recommended by ASHRAE for heat trans-fer coefficients for combined convection and radiation on the outer surface of abuilding are

ho,Winter = 34.0W/m2.Cho,Summer = 22.7W/m2.C

The recommended heat transfer coefficient value for the interior surfaces of abuilding for both summer and winter is

hi = 8.0W/m2.C

For well-insulated buildings, the surface heat transfer coefficients constitute asmall part of the overall heat transfer coefficients, and thus the effect of possibledeviations from the above values is usually insignificant.

2.3.3 Moisture Level

In summer, the moisture level of the outdoor air is much higher than that ofindoor air. Therefore, the excess moisture that enters a house from the outsidewith infiltrating air needs to be condensed and removed by the cooling system.But this requires the removal of the latent heat from the moisture, and the coolingsystem must be large enough to handle this excess cooling load. To size the coolingsystem properly, we need to know the moisture level of the outdoor air at designconditions. This is usually done by specifying the wet-bulb temperature, whichis a good indicator of the amount of moisture in the air. When the wet-bulb andambient temperatures are available, the relative humidity and the humidity ratioof air can be determined from the psychrometric chart. The moisture level ofthe cold outside air is very low in winter, and thus normally it does not affect theheating load of a building.

PSYCHROMETRIC CHARTA psychrometric chart is a graphical representation of the psychrometric pro-

cesses of air. Psychrometric processes include physical and thermodynamic prop-erties such as dry bulb temperature, wet bulb temperature, humidity, enthalpy,and air density. Every psychrometric chart includes vertical lines that representthe dry bulb temperatures. Air temperature increases from left to right.

Figure 2.3: Dry bulb temperature lines on a psychrometric chart

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Every psychrometric chart also includes wet bulb temperatures. These linesare indicated at diagonals, and like dry bulb temperatures they increase from leftto right.

Figure 2.4: Wet bulb temperature lines on a psychrometric chart

The comfort zone is typically indicated by shading a portion of the psychro-metric chart. This shaded area is highly variable per climate and project. Thecomfort zone is either populated by a software system, or manually by a designer,based upon the activity to take place in the building and the level of anticipatedclothing to be worn by the occupants.

Figure 2.5: Comfort zone in a psychrometric chart

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2.3.4 Solar Radiation

Solar radiation plays a major role on the heating and cooling of buildings, andwe may think that it should be an important consideration in the evaluation of thedesign heating and cooling loads. Well, it turns out that peak heating loads usuallyoccur early in the mornings just before sunrise. Therefore, solar radiation doesnot affect the peak or design heating load and thus the size of a heating system.However, it has a major effect on the actual heating load, and solar radiation canreduce the annual heating energy consumption of a building considerably.

2.4 SOLAR AIR TEMPRATURE

The sun is the main heat source of the earth, and without the sun, the environ-ment temperature would not be much higher than the deep space temperatureof −270oC. The solar energy stored in the atmospheric air, the ground, and thestructures such as buildings during the day is slowly released at night, and thusthe variation of the outdoor temperature is governed by the incident solar radia-tion and the thermal inertia of the earth. Heat gain from the sun is the primaryreason for installing cooling systems, and thus solar radiation has a major effecton the peak or design cooling load of a building, which usually occurs early in theafternoon as a result of the solar radiation entering through the glazing directlyand the radiation absorbed by the walls and the roof that is released later in theday.

For opaque surfaces such as the walls and the roof, on the other hand, theeffect of solar radiation is conveniently accounted for by considering the outsidetemperature to be higher by an amount equivalent to the effect of solar radiation.This is done by replacing the ambient temperature in the heat transfer relationthrough the walls and the roof by the sol-air temperature, which is defined as theequivalent outdoor air temperature that gives the same rate of heat transfer to asurface as would the combination of incident solar radiation, convection with theambient air, and radiation exchange with the sky and the surrounding surfaces.

Heat flow into an exterior surface of a building subjected to solar radiation canbe expressed as

Qsurface = hoAs(Tsol−air − Tsurface)

2.4.1 Effect of Solar Heated Walls on Design Heat Load

The west wall of a house which is the only wall which faces the sun is made of100-mm thick brick its heat transfer coefficient is 1.65 W/m2. The exposed surfacearea of the wall is 19.5 m2.Its cooling system is to be sized on the basis of the heat gain at 15:00 hour (3 PM)solar time on July 21, the design ambient air temperature at that time at thatlocation will be 32oC, and the interior of the house is to be maintained at 24oC.According to our calculations temprature on July 21 will be 50oC heat gainthrough that wall will be

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Qsurface=(1.65)x(19.5)x(50-24)

=836.55W

The fraction of heat gain will be

Solar Fraction = 4TTotal

4Tsolar= 16

26= 0.69

Two third of the heat gain is due to this wall.

The outer layer of the wall is made of red brick, which is dark colored.The valueof α is 0.90 for dark and ho is 17 W/m2.oC . Therefore, the value of α

ho=

0.052m2.oC/W .

Solar Fraction Transferred = (1.65)(0.052)=0.086

So, less than 10% of energy will be transferred to house from this red brickwall.

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Chapter 3

Heat Gain from People, Lightsand Equipments

The conversion of chemical or electrical energy to thermal energy in a buildingconstitutes the internal heat gain or internal load of a building. The primarysources of internal heat gain are people, lights, appliances, and miscellaneousequipment such as computers, printers, and copiers. Internal heat gain is usuallyignored in design heating load calculations to ensure that the heating systemcan do the job even when there is no heat gain, but it is always considered indesign cooling load calculations since the internal heat gain usually constitutes asignificant fraction of it.

3.1 PEOPLE

The average amount of heat given off by a person depends on the level of activity,and can range from about 100 W for a resting person to more than 500 W fora physically very active person. Typical rates of heat dissipation by people aregiven in fig.6 for various activities in various application areas. Note that latentheat constitutes about one-third of the total heat dissipated during resting, butrises to almost two-thirds the level during heavy physical work. Also, about 30percent of the sensible heat is lost by convection and the remaining 70 percentby radiation. The latent and convective sensible heat losses represent the instantcooling load for people since they need to be removed immediately. The radiativesensible heat, on the other hand, is first absorbed by the surrounding surfaces andthen released gradually with some delay. It is interesting to note that an averageperson dissipates latent heat at a minimum rate of 30 W while resting. Notingthat the enthalpy of vaporization of water at 33oC is 2424 kJ/kg, the amount ofwater an average person loses a day by evaporation at the skin and the lungs is

Daily Water loss = Latentheatlossperdayheatofvaporization

= (0.030kJ/s)(24x3600s/day)2424kJ/kg

= 1.07kg/day

which justifies the sound advice that a person must drink at least 1 L of water

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every day. Therefore, a family of three will supply 3 L of water a day to the air inthe house while just resting. This amount will be much higher during heavy work.

Figure 3.1: Heat Gain from People in Conditional Space

Heat given off by people usually constitutes a significant fraction of the sensibleand latent heat gain of a building, and may dominate the cooling load in highoccupancy buildings such as theaters and concert halls. The rate of heat gainfrom people given in fig 2.6 is quite accurate, but there is considerable uncertaintyin the internal load due to people because of the difficulty in predicting the numberof occupants in a building at any given time. The design cooling load of a buildingshould be determined assuming full occupancy.

3.2 LIGHTS

Lighting constitutes about 7 percent of the total energy use in residential build-ings. Therefore, lighting can have a significant impact on the heating and coolingloads of a building. Not counting the candle light used for emergencies and ro-mantic settings, and the kerosene lamps used during camping, all modern lightingequipment is powered by electricity. The basic types of electric lighting devicesare incandescent, fluorescent, and gaseous discharge lamps.

The amount of heat given off per lux of lighting varies greatly with the typeof lighting, and thus we need to know the type of lighting installed in order topredict the lighting internal heat load accurately. Incandescent lights are the leastefficient lighting sources, and thus they will impose the greatest load on coolingsystems. So it is no surprise that practically all office buildings use high-efficiencyfluorescent lights despite their higher initial cost. Note that incandescent lightswaste energy by (1) consuming more electricity for the same amount of lightingand (2) making the cooling system work harder and longer to remove the heat

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given off. Office spaces are usually well lit, and the lighting energy consumptionin office buildings is about 20 to 30 W/m2 of floor space.

The energy consumed by the lights is dissipated by convection and radiation.The convection component of the heat constitutes about 40 percent for fluorescentlamps, and it represents the instantaneous part of the cooling load due to lighting.The remaining part is in the form of radiation that is absorbed and reradiated bythe walls, floors, ceiling, and the furniture, and thus they affect the cooling loadwith time delay. Therefore, lighting may continue contributing to the cooling loadby reradiation even after the lights have been turned off. Sometimes it may benecessary to consider time lag effects when determining the design cooling load.

The ratio of the lighting wattage in use to the total wattage installed is calledthe usage factor, and it must be considered when determining the heat gain dueto lighting at a given time since installed lighting does not give off heat unless itis on.

3.3 EQUIPMENTS and APPLIANCES

Most equipment and appliances are driven by electric motors, and thus the heatgiven off by an appliance in steady operation is simply the power consumed byits motor. The power rating Wmotor on the label of a motor represents the powerthat the motor will supply under full load conditions. But a motor usually oper-ates at part load, sometimes at as low as 30 to 40 percent, and thus it consumesand delivers much less power than the label indicates. This is characterized bythe load factor fload of the motor during operation, which is fload = 1.0 for fullload.Also, there is an inefficiency associated with the conversion of electrical energyto rotational mechanical energy. This is characterized by the motor efficiencyηmotor which decreases with decreasing load factor. Another factor that affectsthe amount of heat generated by a motor is how long a motor actually operates.This is characterized by the usage factor fusage with fusage=1.0 for continuousoperation. Motors with very low usage factors are usually ignored in calculations.Then the heat gain due to a motor inside a conditioned space can be expressed as

Qmotor = Wmotor.fload.fusageηmotor

Heat generated in conditioned spaces by electric, gas, and steam appliancessuch as a range, refrigerator, freezer, TV, dishwasher, washing machine, drier,computers, printers are significant, and thus they are being considered when de-termining the peak cooling load of a building. The exhaust hoods in the kitchencomplicate things further. Also, some equipment such as printers, laptops anddesktop computers consume considerable power in the standby mode. A 350-W laser printer, for example, may consume 175 W and a 600-W computer mayconsume 530 W when in standby mode.

A more realistic approach is to take 50 percent of the total nameplate ratingsof the appliances to represent the maximum use. Therefore, the peak heat gainfrom appliances is taken to be

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Qunhooded−appliances = 0.5.Qappliance,input

regardless of the type of energy or fuel used. For cooling load estimate, about34 percent of heat gain can be assumed to be latent heat, with the remaining 66percent to be sensible. In hooded appliances, the air heated by convection and themoisture generated are removed by the hood. Therefore, the only heat gain fromhooded appliances is radiation, which constitutes up to 32 percent of the energyconsumed by the appliance. Therefore, the design value of heat gain from hoodedelectric or steam appliances is simply half of this 32 percent.

3.3.1 USEFUL ENERGY CONSUMPTION

The efficiency of different equipments affects the internal heat gain from themsince an inefficient appliance consumes a greater amount of energy for the sametask, and the excess energy consumed shows up as heat in the living space. Theefficiency of different devices are written

Equipment Efficiency Efficient Load

1. Air conditioner 0.5 0.5x5kW = 2.5kW2. Electric heater 0.2 0.2x2kW = 0.4kW3. Energy Savers 0.9 0.9x1.25kW = 1.125kW4. Smart Tv 0.9 0.9x0.075kW = 0.0675kW5. Ceiling fans 0.8 0.8x1.125kW = 0.9kW6. Desktop Computer 0.5 0.5x0.2kW = 0.1kW7. Electric Kettle 0.4 0.4x1.2kW = 0.48kW8. Fridge 0.7 0.7x0.2kW = 0.14kW9. Electric Iron 0.5 0.5x1kW = 0.5kW10. Microwave 0.5 0.5x2kW = 1kW11. Table Fan 0.7 0.7x0.1kW = 0.07kW12. Toaster 0.5 0.5x1kW = 0.5kW13. Washing Machine 0.8 0.8x0.5kW = 0.4kW14. Water pump 0.6 0.6x2kW = 1.2kW15. Charging devices 0.8 0.8x0.02kW = 0.016kW16. Exhaust Fans 0.8 0.8x0.1kW = 0.08kW17. Printer 0.6 0.6x0.1kW = 0.06kW18. Laptop Computer 0.8 0.8x0.1kW = 0.08kW19. Exhaust Hood 0.7 0.7x0.15kW = 0.105kW

Out of the total base load which was equal to

18.63 kW useful energy is 9.72 kW.The remaining energy is wasted as a heat during the running of these appliancesand it should be kept in mind while designing our cooling system.

Page 13

Chapter 4

Heat Loss due to Appliances

4.1 FANS

Three fans which are used frequently during the year have fload = 0.6,fusage = 1.0, ηfans = 0.8 and the heat gains due to these fans are

Q=3 x 75 x 0.6 x 10.8

= 168.75 W

Remaining twelve fans emits heat equal to

Q=12 x 75 x 0.1 x 10.8

= 112.5 W

The heat gain due to cieling fans per year is equal to

Qtotal= 168.75+112.5=281.25 W

4.2 Air Conditioner

Air conditioners which are used frequently during summer season fload = 0.11,fusage = 1.0, ηAC = 0.5. The heat gain due to air conditioners per year is equal to

Qtotal= 2 x 2500 x 0.11 x 10.5

=1100 W

4.3 Electric Heater

Electric Heater which is used frequently during winter season fload = 0.01,fusage = 1.0, ηheater = 0.2 and the heat gain due to electric heater per year is equalto

Qtotal= 2000 x 0.01 x 10.2

=100 W

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4.4 Energy Savers

Ten Energy savers which are used frequently during the year have fload = 0.2,fusage = 1.0, ηsavers = 0.9 and the heat gains due to these energy savers are

Q= 10x25 x 0.2 x 10.9

=55.5 W

Forty Energy savers which are used rarely during the year have fload = 0.05,fusage = 1.0, ηsavers = 0.9 and the heat gains due to these energy savers are

Q= 40x25 x 0.05 x 10.9

=55.5 W

The heat gain due to energy savers per year is equal to

Qtotal= 55.5 + 55.5=111 W

4.5 Smart TV

Smart Tv which is used frquently during the year has fload = 0.42,fusage = 1.0, ηTV = 0.9 and the heat gains due to this smart TV is

Qtotal= 75 x 0.42 x 10.8

=39.37 W

4.6 Desktop computer

Desktop computer which is used rarely during the year has fload = 0.05,fusage = 1.0, ηcomputer = 0.5 and the heat gains due to this desktop computer is

Qtotal= 200 x 0.05 x 10.5

=20 W

4.7 Electric Kettle

Electric Kettle which is used very rarely during the year has fload = 0.005,fusage = 1.0, ηkettle = 0.4 and the heat gains due to this electric kettle is

Qtotal= 1200 x 0.005 x 10.4

=15 W

4.8 FRIDGE

Fridges which are used very frequently during the year has fload = 0.91,fusage = 1.0, ηfridge = 0.7 and the heat gains due to these fridges is

Qtotal= 2 x 200 x 0.91 x 10.7

=580 W

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4.9 Electric Iron

Electric Iron which is used rarely during the year has fload = 0.03,fusage = 1.0, ηiron = 0.5 and the heat gains due to this iron is

Qtotal= 1000 x 0.03 x 10.5

=60 W

4.10 Microwave

Microwave which is used rarely during the year has fload = 0.017,fusage = 1.0, ηmicrowave = 0.5 and the heat gains due to this microwave is

Qtotal= 2000 x 0.017 x 10.5

=68 W

4.11 Table Fan

Table fan which is used rarely during the year has fload = 0.011,fusage = 1.0, ηfan = 0.7 and the heat gains due to this table fan is

Qtotal= 100 x 0.011 x 10.7

=1.57 W

4.12 Toaster

Toaster which is used very rarely during the year has fload = 0.002,fusage = 1.0, ηtoaster = 0.5 and the heat gains due to this toaster is

Qtotal= 1000 x 0.002 x 10.5

=4 W

4.13 Exhaust Fans

Exhaust Fans which are used very frequently during the year has fload = 0.68,fusage = 1.0, ηExhaust = 0.8 and the heat gains due to these exhaust Fan is

Qtotal= 2 x 200 x 0.68 x 10.8

=340 W

4.14 Washing Machine

Washing Machine which is used very rarely during the year has fload = 0.011,fusage = 1.0, ηMachine = 0.8 and the heat gain due to this Washing Machine is

Qtotal= 500 x 0.011 x 10.8

=6.875 W

4.15 Water Pump

Water pump which is used frequently during the year has fload = 0.5,fusage = 1.0, ηPump = 0.6 and the heat gain due to this Water Pump is

Qtotal= 2000 x 0.5 x 10.6

=1666.67 W

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4.16 Charging Devices

Charging Devices which are used frequently during the year has fload = 0.68,fusage = 1.0, ηdevices = 0.8 and the heat gain due to these Charging Devices is

Qtotal= 5x4 x 0.68 x 10.8

=17 W

4.17 Printer

Printer which is used rarely during the year has fload = 0.114,fusage = 1.0, ηprinter = 0.6 and the heat gain due to this Printer is

Qtotal= 100 x 0.114 x 10.6

=19 W

4.18 Laptop Computers

Laptops which are used frequently during the year has fload = 0.685,fusage = 1.0, ηLaptop = 0.8 and the heat gain due to these Laptops is

Qtotal= 2 x 50 x 0.685 x 10.8

=85.625 W

4.19 Exhaust Hood

Exhaust hood which is used frequently during the year has fload = 0.45,fusage = 1.0, ηhood = 0.7 and the heat gain due to this exhaust hood is

Qtotal= 150 x 0.45 x 10.7

=96.42 W

TOTAL HEAT LOSSThe total heat loss during year and for a single month is as follows:

Heat loss for a year Q(KWh) = 1500

Heat loss for a month Q(KWh) = 125

Page 17

Chapter 5

Solar Power Generation

5.1 Introduction

When we capture solar energy it can be either used as heat or electrical energy.for this two systems are used.

5.1.1 Thermal Systems

In this system sunlight is captured by falling it on the solar collector and thisis used in heating of water or for space heating, but the heat can also used togenerate electricity by focusing the heat on the heat absorber in which workingfluid is present which is used to raise steam which in turn drives a generator andturbine in a separate circuit.

5.1.2 Photovoltaic Systems

In Photovoltaic Systems radiant energy of sunlight is used and converted to elec-trical energy by focusing sunlight on the photovoltaic cells.

The amount of energy produced is directly proportional to the area of thecollector which is facing the sun.

5.2 Solar Collectors

It is the heat collecting surface on which sunlight falls and this radiant energy ofsun is used to heat up the thermal working fluid.

5.2.1 Concentrators

In concentrators all the sun light is focused on the small receiver so that we canattain higher temperature easily and early for the working fluid.The unit of solar concenterator is suns. It have different types which are explainedbelow.

18


• Parabolic Trough.It consists of rows of parabolic-shaped mirrors that reflect and concentrate

sunlight onto linear receivers located along the foci of the parabolas. The receivers,or heat collection elements , consist of a stainless steel absorber tube surroundedby a glass envelope with the vacuum drawn between the two to reduce heat losses.A heat transfer fluid circulates through the receivers, delivering the collected solarenergy to a somewhat conventional steam turbine/generator to produce electricity.

Figure 5.1: Parabolic trough

• Power Tower.In this large number of plates are present and all the sunlight which falls on

these plates is concenterated on the tower on which solar furnance is present andthis solar furnance is used to make steam to run steam turbine in return.In thissolar plates are fixed on their axis.

Figure 5.2: Power Tower

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• Heliostat.It is similar to power tower but in this all the plates which focus all the sunlight

on the tower are basically sun tracking mirrors which moves with the direction ofsun and falls all the sunlight to the tower in return.

Figure 5.3: Heliostat

• Parabolic Dish.In it heat absorber is present at the focus of the parabolic shaped dish. When

sunlight falls, all the light is used to rise the temperature which is proportionalto the area of the dish such that by increasing the area of the dish we can getmore temperature on the absorber of the parabolic dish. It is used for the systemsbetween 20kW to 40kW.

Figure 5.4: parabolic dish

Page 20

Chapter 6

Production of Electricity throughSunlight

6.1 Introduction

During night when there will be no sun and hence no power will be provided bythe solar system so there must be a system that generate amount of energy so thatit can fulfill the day time requirement and has ability to store enough energy fornights or if there is no sunlight available due to bad weather. We will use batteriesto provide electrical energy during night and during bad weather when there is nosunlight, but it is not possible for us to store large amount of energy.

6.2 Thermal Power

Electricity in a solar thermal plant is produced in two steps.• Heat energy from the sun is captured and is used to heat the working fluid.• This working fluid is used to generate electrical energy.Thermal power plant have set of mirrors on which sunlight is focused and is usedto heat the absorber which run the turbine for electricity production. On largescale, the heat engine is usually a turbine driven by steam or some other workingfluid. In small scale systems the heat engine may be a Stirling engine.

6.2.1 Large Scale production

In large scale production solar plates are present which capture sunlight and focusall of it on the single concentrator which transfers heat to heat exchanger. Thisheat exchanger further transfer heat to run steam turbine and steam turbine alongwith steam generator gives electrical energy which is used further for other pur-poses .Each module requires large area of land and need very accurate engineeringand control. The type of system used in large scale is shown below.

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Figure 6.1: Large scale production

6.2.2 Small Scale production

There are more than one technique in Small scale production.

• Photovoltaic SystemsThe simplest technique used in domestic purpose is the solar panels which cap-

ture the sunlight and then it is converted into DC after passing through regulatortransfers to DC control unit. This control unit is attached with battery bank andwith the inverter. DC control unit gives its DC supply to inverter which convertsit to AC. After the conversion it is used to lighten our houses.

Figure 6.2: Photovoltaic System

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• Voltaic SystemIn this solar power is directly converted into electricity. The light falls on the

solar panel this light is converted into electricity for direct usage but this onlyhappens when sunlight is present. This system will not work when there is nosunlight. This system is used in watches, calculators and mobile chargers.

Figure 6.3: Voltaic System

• Solar StirlingIn this solar energy is converted to thermal and used to run stirling engine

which is further used to run generator to produce AC supply. When there is noexternal use the energy is stored in battery after the conversion of AC to DC.These batteries are used as a backup power when needed.

Figure 6.4: Solar Stirling

Page 23

Chapter 7

Heating from Solar Power

7.1 Introduction

In many cases solar power is used only to heat up the water. This is done in sucha way that solar plates heat up the heat exchanger in which working fluid is waterwhich we have to heat up. This water is passed through heat exchanger whichconsists of coiled pipe and then enters to hot water storage tank so that it can beused. In such a way we heat up our water indirectly through solar system. Thisis called solar water heating system.

7.2 Solar Water Heating

Solar water heating systems include storage tanks and solar collectors. There aretwo types of solar water heating systems:• Types of Solar Water Heating

There are two types of solar water heating systemActive Solar Water Heating SystemPassive Solar Water Heating System

but we are using active solar heating system as it is less complicated and easy todesign.

7.2.1 Active Solar Water Heating System

There are furthur two types of active solar water heating systems:

• Direct Circulation SystemPumps circulate household water through the collectors and pass it into the

home for usage. They work well in weather conditions where it rarely freezes.• Indirect Circulation System Pumps circulate a non-freezing, heat-transferfluid through the collectors and a heat exchanger. This heats the water that flowsinto the home. They are popular in climates prone to freezing temperatures.

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MethodologyIn this system we use flat plate collectors which captures sunlight and this

sunlight is used to heat the working fluid which is water and this water whenheats up due to sunlight is sent to heat exchanger which consists of coiled pipeand this heat exchanger is linked with hot water storage tank and the portion ofhot water storage tank is also present in kitchen of our house when this hot waterstorage tank gets heated due to heat exchanger in which warm water flows thenthe water present in hot water storage tank is used in house and the body of hotwater storage tank is used for cooking purpose carefully.

Figure 7.1: Active Solar Water Heating

7.3 Storage Tanks And Solar Collectors

Most solar water heaters require a well-insulated storage tank. Solar storage tankshave an additional outlet and inlet connected to and from the collector. In one-tank systems, the back-up heater is combined with the solar storage in one tank.Three types of solar collectors are used for residential applications:• Flat Plate Collector• Integral collector-storage systems• Evacuated-tube solar collectors

7.3.1 Flat Plate Collector

Glazed flat-plate collectors are insulated, weatherproofed boxes that contain a darkabsorber plate under one or more glass or plastic (polymer) covers. Unglazed flat-plate collectors – typically used for solar pool heating – have a dark absorber plate,made of metal or polymer, without a cover or enclosure.

Page 25


7.3.2 Integral collector-storage systems

Also known as ICS or batch systems, they feature one or more black tanks or tubesin an insulated, glazed box. Cold water first passes through the solar collector,which preheats the water. The water then continues on to the conventional backupwater heater, providing a reliable source of hot water. They should be installedonly in mild-freeze climates because the outdoor pipes could freeze in severe, coldweather.

7.3.3 Evacuated-tube solar collectors

They feature parallel rows of transparent glass tubes. Each tube contains a glassouter tube and metal absorber tube attached to a fin. The fin’s coating absorbssolar energy but inhibits radiative heat loss. These collectors are used more fre-quently for U.S. commercial applications.In our house we are using flat plate collector for heating purpose.

7.4 Room Air Heaters

Air collectors can be installed on a roof or an exterior (south-facing) wall for heat-ing one or more rooms. Although factory-built collectors for on-site installationare available, do-it-yourselfers may choose to build and install their own air collec-tor. A simple window air heater collector can be made for a few hundred dollars.The collector has an airtight and insulated metal frame and a black metal platefor absorbing heat with glazing in front of it. Solar radiation heats the plate that,in turn, heats the air in the collector. An electric fan or blower pulls air fromthe room through the collector, and blows it back into the room. Roof-mountedcollectors require ducts to carry air between the room and the collector. Wall-mounted collectors are placed directly on a south-facing wall, and holes are cutthrough the wall for the collector air inlet and outlets.

7.4.1 Methodology

In our house we are installing Air collectors on a roof for heating the house andthe thermostat is present between the Air collector and the internal temperatureof the house when the temperature of the internal temperature is 10 times lessthan the temperature of air collector then the thermostat allows the fan which ispresent along with the air collector and which runs with the thermal energy forwhich separate plate is attached to turn on and allow the cold air of internal houseto circulate from the air collector to heat up and enters in the house again.Duringsummer season this thermostat can be tripped manually.

7.5 Installing The System

The proper installation of solar water heaters depends on many factors. Thesefactors include solar resource, climate, local building code requirements, and safety

Page 26


issuesFor our house we use 50 gallons of hot water storage tank and in its thermostatplays the key role for heating system and this thermostat can be tripped manu-ally.The heart of the control system is a differential thermostat, which measuresthe difference in temperature between the collectors and storage unit. When thecollectors are 15 to 25oF (7 degree to 15 oC) warmer than the storage unit, thethermostat turns on a pump or fan to circulate water or air through the collectorto heat the storage medium or the house.

7.6 Calculation of Heat Energy from Hot Water

The required temprature of water is 75oC.The temperature of Source Water = 25oC.The desity of water is =1000kg/m3.The Specific heat of water = 4.18 KJ/KgoC.The water supply for family of three is 3x 70L/day = 210Liter/day

The energy for heating water is

qhw(t) = pw.Q(t).cpw.[Td − Ts]

putting values in equation we get 71450kJ/dayfor one month value of energy is 71450 x 30 = 2.1MJ/month• System Design

Figure 7.2: Open loop Water Heating

Page 27

Chapter 8

Cooling From Solar power

Many of us will wonder after seeing this cooling from solar power but it is possibleand there are different methods

8.1 Flat Plate Collector

Flat-plate collectors are the most widely used kind of collectors for domestic water-heating systems and solar space heating/cooling. A typical flat plate collector con-sists of an absorber, transparent cover sheets, and an insulated box. The absorberis usually a sheet of high thermal conductivity metal such as copper or aluminium,with tubes either integral or attached. Its surface is coated to maximise radiantenergy absorption and to minimise radiant emission. The insulated box reducesheat loss from the back or the sides of the collector. The cover sheets, calledglazing, allow sunlight to pass through the absorber but also insulate the spaceabove the absorber to prevent cool air to flow into this space.

8.2 Desiccant cooling system

Desiccant cooling systems are basically open cycle systems, using water as a re-frigerant in direct contact with air. The thermally driven cooling cycle is a com-bination of evaporative cooling with air dehumidification by a desiccant. For thispurpose, liquid or solid materials can be employed. The term open is used to indi-cate that the refrigerant is discarded from the system after providing the coolingeffect, and new refrigerant is supplied in its place in an open-ended loop. Thecommon technology applied today uses rotating desiccant wheels, equipped eitherwith silica gel or lithium-chloride as sorption material. For the choice of the typeof chillers, the following parameters have to be evaluated in advance:• The operating temperatures of the absorption machine, as they affect the choiceof solar collector.• The values of the coefficient of performance (COP) of the chiller, as theychange according to the above mentioned temperatures and also according to theheat distribution system installed (e.g. fan-coils or radiant floor).The choice of the type of solar collectors is not a difficult task. The function-

28


ing temperature of the absorption chiller determines the most suitable typologyof collectors for different layouts. Dimensioning of the panels surface follows thesame rules of domestic solar plants for hot water production, even though the factthat a solar cooling plant operates at higher temperatures has to be taken intoaccount.

Page 29

Chapter 9

Design of System

9.1 Diagram

Figure 9.1: Design

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