HNICEM2005.pdf

Second Humanoid, Nanotechnology, Information Technology, Communication and ControlEnvironment and Management (HNICEM) International Conference

March 24-27, 2005, Manila Pavilion, Manila, Philippines

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POTENTIAL ELECTRICITY SAVINGS BY VARIABLE SPEED CONTROLOF COMPRESSOR FOR AIR CONDITIONING SYSTEMS

ABSTRACTVariable speed at compressor by using ofmanual (without control system) and controlsystem have been purposed in air conditioningsystem, it has big potency in the effort of usageelectrics energy saving. In this research, theusage of central type air conditioning withcapacities 3 kW, with nominal motor rotation is1450 rpm. Base on reference, the roomtemperature is 22 o C while the motor rotationvariation are : 20, 25, 30, 35, 40, 45, and 50 Hz.Our results indicated that the value of electricenergy saving consumption is 20,77 % at motorfrequency 40 Hz, and 22,54 % by usingproportional control systems.

Key Words – Energy saving, variable speedcontrol, proportional control, air conditioning.

I. INTRODUCTION

Energy conservation, is begins with an action toreduce demand for energy in an individualcountry, and now has become a subject ofregional and even worldwide discussion. It is notonly can be applying on a new design system butalso on retrofit projects [1]. As long as its fulfillthe energy saving condition, and also have thelowest or minimum energy consumption, will besatisfied for the consumer needed, theconservation strategies can be implemented. Sothat problem is become compulsion which mustbe fulfill for every registered in state is ProtocolKyoto [2].

The solution of energy saving at high building iswith usage of electrics for the air conditioningand lighting can be decreased by as low aspossible, because energy usage in building can

reach 90 % for the air conditioning and lighting[3]. At the air conditioning system, energy usagewhich many at compressor, equal to 90 % fromtotalizing of electrics energy [4].

Since 1970 to 1991, the number of airconditioners have been increased from 1325units to 253 399, and on 2020 it will be 1 511276 [5-7]. Otherwise in 2000, base on the datathat have been collected in Jakarta, from 960 000high building only 50 building have been usedstandard number usage of energy [8-9]. It willgive a significant impact on the future electricityconsumption in this country.

Since 1982 to 2002, only 10 papers related to thisresearch. Two papers present adjustable speed ofcompressor for air conditioning by using controlsystem such as PID control (Krakow, 1995) andOn – Off control ( Koury, 2001) with numericalor simulation methods [11]. In another papersonly with manual (not used the control system)adjustable speed control of compressor. There arenot many research about this topic because it havebeen delayed to setting of control system, It isdifferent with the setting of control system ofmodel equipment that needed an inverter andcontroller as additional equipment (needadditional cost). If we refer to minimum energyefficiency for air conditioning, energy crisis(specifically for fuel energy), if the renewableenergy is not available, this problem must bedone. There are many country in the world likeAustralia, Brazil, Canada, China, Europe, Japan,Korea, Mexico, Philippine, Russia and US havebeen enacted minimum energy efficiencystandards for appliance. This programs can bemandatory (i.e., government law or regulation) orvoluntary (i.e., agreement with manufacturers)[6].

HENRY NASUTIONMechanical Engineering Department,

Bung Hatta University, 25143 - PadangWest Sumatera - Indonesia

Email : [email protected]

MAT NAWI WAN HASSANMechanical Engineering Faculty,

Universiti Teknologi Malaysia, 81310Johor Bahru, Johor – Malaysia Email : [email protected]

mailto:[email protected]

mailto:[email protected]



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II. VARIABLE SPEED MOTOR ANDCONTROL SYSTEM

2.1. Variable speed motor of compressorIn general, air conditioning was consumed 40 %to 90 % of the total electrical energy incommercial buildings, it is imperative thatenergy and cost saving measure are undertakento minimize the wasteful use of energy [10].Several energy saving methods were proposedfor better control and monitoring of airconditioning, which are : building automationsystem (BAS), duty cycling, peak load shaving,solar film, variable speed motors, and thermalenergy storage [1].

To regulate the motor speed is by using theinverter. Which can variation the rotation base onchange frequency, while current and voltage ofmotor do not experience of change. Because ininverter system, frequency will be proportionalits change to rotation, voltage, current and powerelectric. With the equipments, motor canfluctuate the condition according to the neededand do not experience of damage trouble.

The implementation of variable speed for thecompressor has been selected as a means toinvestigated the reliability and compatibility ofvariable speed compressor in capacity andenergy control. Since energy consumed by acompressor in an air conditioning system is thehighest than other component, it is naturally wiseto consider the energy saving in the compressor.However, saving in energy consumption of thecompressor is very important since it will reducethe energy consumption of the systemsignificantly.

One effort for the energy saving that usage in airconditioning and heat pump system is with makea variation of motor speed, this matter havebeen conducted by some researcher like : Lloyd(1982), Ishii (1988), Rieger (1988), Miller(1988), Garstang (1990), Ishii (1990),Takebayashi (1994), Norlidah (1995), Krakow(1995), Qureshi and Tassou (1998), Kim et. al(1998), and Park (2001). The other method iscapacities variation of refrigerant have done byHirano and Shigeoka (1990). More wholly seeTables 1 [2,11].

2.2. Control system air conditioningConventional air conditioning control system arerun on a fixed setting throughout the day, withtarget the value of room temperature for thebuilding facility space. The control center of thebuilding used to be unable to change this fixedsetting even in cases in which the setting led toenergy being wasted as a result of excessiveheating or cooling. The principle is the target setvalues for the room temperature should or couldbe changed more finely to suit the constantlychanging room environment did not exist.

Control systems is very important in airconditioning system when the system is designedto operate it automatically. These control methodsmay utilize differences between space and setpoint values of temperatures, subsequently, tocontrol motor speeds.

The features of an energy-saving air conditioningcontrol system as part of a local controlconfiguration designed for extensibility andreliability in the total building control.

III. EXPERIMENTAL PROCEDURE

The experiment have been established with thefollowing procedure : running of the constantspeed compressor or the compressor workingnominal speed about 50 Hz (fixed speed). Theresults obtained will be used later as a datacomparative with the variable speed compressor.The second procedure, is testing on thecompressor base on the different of frequencysetting, it must be conducted prior to the variablespeed compressor tests. The aim providing thedata reference on the compressor like by usingARTDRiveG (AGy2055-KBX type inverter) asspeed control used, that are related to thelimitation range of temperature set points, outputvoltage, current and frequency of the motor andpower and also energy used. In this condition, itis will be specified : temperature set point is 22 o

C, minimum and maximum motor frequency are20 and 50 Hz. The next procedure, controlapplication for variable speed by controlling therotation of motor compressor with proportionalcontrol type of usage. These control methodsmay utilize differences between space and setpoint values of temperatures, subsequently, tocontrol motor speeds.



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This research were conducted during 3 hours,while the data have been collected by interfaceconnected (Advantech PCI-1711/PCLD-8710)every 5 minutes. It can be seen and saved in thecomputer, enable the user to see the event in thesystem environment. Displaying of data is roomtemperature and variable features of motor(frequency, power, voltage, current, and speed).The installation of experimental is shown in Fig.1.

IV. RESULT AND DISCUSSION

Fig.2, Fig.3, and Table 2 is shown that ACoperated timing will be increase at frequency50 Hz and it will decreasing the roomtemperature at ( 19 o C), by using of constantspeed energy value at 2,5 kW. Variation offrequency at : 20, 25, 30, 35, 40, 45, and 50 Hzwill influence the reaching of temperaturevariation at : 23.9, 22.1, 21.3, 21.0, 20.2, 19.3,and 19 o C, while energy consumption is 0.96to 2.55 kW.

Fig.2 Temperature distribution

Specified temperature of reference is 22 o C andat this condition it can reach the frequency at25 Hz. This event is not efficient becausereached temperature of reference was needed along time.

Although effort for the save energy consumptioncontinue to be strived, temperature remain to beindicator to user. For that the effort taken withusage of control systems able to fulfill two thecondition above. Proportional control systemshave been used in the first steps of this research,while temperature of reference is the same as

room temperature by using of energy withcapacity as small as posible. In Table 2, is shownthat energy fluctuation will so that temperatureof reference condition reached. During thesystem condition is reaching and stabilize, themotor will operate on minimum frequency at 20Hz, and given load in room, next the systemwill operate the specified condition which(temperature of reference condition).

Fig.3 Energy consumption

From experimental was shown that, to saveenergy consumption can be solving by made avariation of frequency and this condition wasalso depended on temperature of reference. Byusing of proportional control system, it can saveenergy consumption of 22,54 % toward ACstandard operation. Without using control system,the condition of AC operation admit to bedegraded up to frequency 40 Hz, can save energyconsumption equal to 20,77 % toward 50 Hzfrequency.

V. CONCLUSION

The application of variable speed control to airconditioning offers the potential for substantialenergy savings or energy efficiency. In variablespeed control application, the compressor speedwill influence various operating and designparameters such as cooling load, powerconsumption, COP, volumetric and isentropicefficiency. Variable speed control indicate thatspace temperature may be controlledsimultaneously by the simultaneous operation ofcompressor speed, with the result that operationof compressor speed to adapted of temperature(cooling load) changing. In this system is one of



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the actions to develop minimum energyefficiency for renewable energy.

ACKNOWLEDGEMENT

The author acknowledge support provided byBung Hatta University and Universiti TeknologiMalaysia for this research. We thanks to, Fluidand Thermal Laboratory of Faculty MechanicalEngineering.

REFERENCES

[1] Norlidah Zainal Abidin, “Retrofitting ofCompressor Motor in Air ConditioningSystem for Energy Saving ”, UniversitiTeknologi Malaysia : Masters Thesis,1995.

[2] Henry Nasution, “ Hemat Energi padaSystem “Air Conditioning” SebagaiUpaya Mengatasi Krisis Energi diIndonesia “, TIMI2004 Proceeding,London, pp. 022-1 – 022-6, September 11- 12, 2004.

[3] Kompas, “Merancang gedung ramahlingkungan”, September 22, 2002.

[4] K. Tojo et al., “A Scroll Compressor for AirConditioners”, Proc. InternationalCompressor Engineering Conference atPurdue, pp. 496-503, 1984.

[5] T.M.I Mahlia, H.H.Masjuki, andI.A.Choudhury., “ Potential electricity

savings by implementing minimum energyefficiency standards for room airconditioners in Malaysia”, EnergyConversion and Management, vol.42, pp.439 – 450, March, 2001.

[6] T.M.I Mahlia, H.H.Masjuki, andI.A.Choudhury, “ Potential electricitysavings by implementation energy labelsfor room air conditioner in Malaysia”,Energy Conversion and Management,vol.43, pp. 2225 – 2233, November, 2002.

[7] T.M.I Mahlia, H.H.Masjuki, andI.A.Choudhury, “ Development of energylabels for room air conditioner inMalaysia : Methodology and Results”,Energy Conversion and Management,vol.43, pp. 1985 – 1997, October, 2002.

[8] Kompas, “Minim, sarana kebakaran digedung bertingkat di Jakarta”, March 22,2003.

[9] Kompas, ”Pengusaha belum lakukanefisiensi”, May 22, 2001.

[10] Mohd Yusoff bin Senawi, “Development ofa Building Energy Analysis Package(BEAP) and Its Application to TheAnalysis of Cool Thermal Energy StorageSystems”, Universiti Teknologi Malaysia :PhD Thesis, 2001.

[11] Henry Nasution,” Variable speed drives ofreciprocating compressor for airconditioning : Literature review”,SAINSTEK, vol.VI, no.1, pp.25-39,September, 2003.

Fig.1 Experimental apparatus



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Table 1. Related research of control system for air conditioning



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(continued)



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Table 2. Experimental result

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HNICEM2005.pdf