Air Conditioning System using Thermal Energy Storage with PCM: a state of art A REVIEWSubmitted

In partial fulfillment of

The requirement for the award of degree

 B.TECH

IN

MECHANICAL ENGINEERING

Submitted By Guided by

Indrajeet Kumar Mr. Hari Kumar Singh

SURESH GYAN VIHAR UNIVERSITY

MAHAL, JAGATPURA, JAIPUR

INDIA 302025

October 2015

INTRODUCTION 

Thermal energy storage (TES) is a technology that stocks thermal energy by heating or cooling a storage medium so that the stored energy can be used at a later time for heating and cooling applications and power generation.

TES systems are used particularly in buildings and industrial processes. In these applications, approximately half of the energy consumed is in the form of thermal energy, the demand for which may vary during any given day and from one day to next.

OBJECTIVE Thermal energy storage with PCM is capable of storing and releasing large amounts of energy.

The system depends on the shift in phase of the material for holding and releasing the energy. For instance, processes such as melting, solidifying or evaporation require energy.

Heat is absorbed or released when the material changes from solid to liquid and vice versa.

Therefore, PCMs readily and predictably change their phase with a certain input of energy and release this energy at a later time.

Our project will focus on using PCM as thermal storage for air conditioning and to calculate:

1. Change in enthalpy for heat absorption2. Time of storage3. Economic and social benefits

STORAGE TYPE

 Mechanical Energy Storage : include gravitational energy storage or pumped hydropower storage (PHPS), compressed air energy storage (CAES) and flywheels.

 Electrical Storage : through batteries is an option for storing the electrical energy.

 Thermo-chemical Storage : energy absorbed and released in breaking and reforming molecular bonds in a completely reversible chemical reaction. In this case, the heat stored depends on the amount of storage material, the endothermic heat of reaction, and the extent of conversion.

Thermal Energy Storage : can be stored as a change in internal energy of a material as :o Sensible Heat Storageo Latent Heat Storageo Thermochemical Storage

Why Thermal Storage ?

Limited electric power.

Loads are of short duration, infrequently, cyclical in nature

Loads are not well matched to the availability of the energy source

Energy costs are time-dependent (e.g., time-of-use energy rates or demand charges for peak energy consumption)

Classification of cool thermal energy storage

Latent..heat…storage

Latent heat is defined as heat absorbed or rejected by PCMs during transformation of phase

(solid-solid, solid-liquid, liquid-vapor and vice versa) at constant or nearly constant

temperature. Figure shows temperature and heat variations for sensible (material x) and latent

heat storage (material y) materials during heat transfer process. Charging of thermal storage for

material x process A to B denotes sensible heat addition (continuous increase in temperature),

B to C latent heat absorption (constant temperature), C to D sensible heat addition (continuous

increase in temperature). Charging of thermal storage for material y process A to B denotes

only sensible heat absorption.

Different   behaviors of sensible and latent heat storage materials for temperature and heat variations.

Selection of PCMs

The PCM to be used in the design of thermal storage system should posses desirablethermo physical, kinetic ,chemical and economic properties, which are recommended as follows .

Thermo physical properties

(i) Melting temperature in the desired operating temperature range.

(ii) High latent heat of fusion per unit volume.

(iii) High thermal conductivity .

(iv) Small volume change on phase transformation ..

(v) Congruent melting of the phase change material.

Kinetic properties

(i) High nucleation rate

(ii) High rate of crystal growth.

Chemical properties

(i) Complete reversible freeze/melt cycle.

(ii) No degradation after a large number of freeze/melt cycle.

(iii) Non corrosive

(iv) Non-toxic, non-flammable and non-explosive material for safety.

Economics properties

(i) Abundant.

(ii) Available.

(iii) Cost effective.

Components of TES –Air Conditioning :

Fabrication of System : Main unit (compressor,condenser)

INSULATING CHAMBER OF GALVANIZED ALUMINIUM SHEETINSULATING MATERIAL POLY UREATHANE FOAM

Fabrication of Storage System : Auxiliary Unit ( PCM, Blower, Expander, Expansion Valve)

Performance Analysis 

1. To calculate change in enthalpies for Heat Absorption capacity.2. To calculate Time of storage i.e., time of charging.3. To calculate Social and Economic benefits.

Thanks