# Efficiency Improvement of Thermal Energy Storage using PCM

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#### Efficiency Improvement of Thermal Energy Storage using PCM

Ramkumar. G

Department Of Mechanical Engineering, Bharathidasan Engineering College, Natrampalli, Tirupattur, Tamil Nadu, India

Abstract:- Thermal energy storages tank are effective storages and retrieval of heat energy for solar thermal application. Thermal energy storage is normally Sensible Heat Storage (SHS). One another kind of combined thermal energy is Latent Heat Storage (LHS). Phase Change Material (PCM) is used in latent heat storage. Reduce the time required while storing and releasing heat in latent heat storage system for solar thermal application. During these processes phase change material is melted and solidified. The performance of combined sensible thermal energy and latent thermal energy is greater than sensible heat energy.

Keywords: component; sensible heat, latern heat, PCM

1. INTRODUCTION
1. SENSIBLE THERMAL ENERGY STORAGES

That is, the internal energy of the storages material is influencing by the energy going stored, which would raise the temperature of the materials.

Expressed equation Q = mcp (T1-T2)

Where Q is heat transfer

Cp is specific heat of water

2. LATENT THERMAL ENERGY STORAGE:

In latent TES, the heat storages material undergoes a phase transformation process for storing or discharging the heat energy [1]. The phase change material either from solid to liquid or near isothermal condition.

Sensible heat energy = ( )

Latent heat energy Q = m (^H)

Q = mcp(T1-T2)+m(^H)+Mpcm cp(Tf-Tw)

2. PHASE CHANGING MATERIALS

Thermal energy storage through PCM is capable of storing and releasing large amount of energy. The system depends on the shift in phase of the material for holding and releasing the energy [2].

1. PARAFFIN WAX

Paraffin wax refers to a mixed of alkanes that fall with 20 n 40 range. They are found in the solid state at room temperature and begin to either liquid phase approximately 37Â°C.

Fig.1 Thermal energy storage using PCM

3. EXPERIENTAL SETUP COMPONENT
1. Thermal storage tank
2. RTD
3. Temperature indicator
4. Insulation material
5. Phase change material
6. Flow meter
7. Pressure gauge
1. THERMAL STORAGE TANK:

Thermal storage tank is heat water storage in occupies space. Tank has manufacturing stainless steel. The tank is two position one outer tank and other inner tank.

Fig.2 Thermal storage tank

There are two physical systems namely LHS system and SHS system considered in the present analysis [3]. The LHS system considered for the analysis is a cylindrical storage system of height 1100 mm and diameter 500 mm. It consists of three zones.

2. RTD

RTD is a temperature sensor which measure temperature using the principles that the resistance of the metal charge with temperature.

Fig.3 PT100 RTD sensor (platinum resistance element)

• Outer diameter: 6 mm
• Length of platinum element: 4 inch or 101.6 mm
• Cable length or lead wire: 4 meter
• Cable insulation: pt fe insulation
• Configuration: 3 wire configuration
• Temperature range: 20Â°C TO 540Â°C
3. TEMPERATURE INDICATOR:

Temperature indicators used to indicate or measuring the temperature at corresponding area. Using thermal indicators are 12 cable connections with two segments (red and white). Temperature range measure 20Â°C TO 550Â°C. Digital temperature is measured.

Fig.4 Temperature Indicator

4. INSULATION MATERIAL

Thermal insulation is blocking or reducing heat transfer between two objects (heat transfer is energy moving from one thing to another because of a difference in temperature) [4]. Thermal conductivity is 0.028 W/m.k

Fig.5 Thermal Insulation

5. PHASE CHANGE MATERIAL

Table: 1 Variation Values of PCM

6. FLOW METER

A mass flow meter, also known as an inertial flow meter is a device that measures mass flow rate of a fluid traveling through a tube [5]. The mass flow rate is the mass of the fluid traveling past a fixed point per unit time.

7. PRESSURE GAUGE

Pressure gauge, instrument for measuring the condition of a fluid (liquid or gas) that is specified by the force that the fluid would exert, when at rest, on a unit area, such as pounds per square inch or new tons per square centimeter [6]. Pressure gauge ranges from 0 to 5-bar.

4. EXPERIMENTAL ANALYSIS Table: 2 Analysis of Sensible Heat
 Time Solar radiation Ta Ti To T1 T2 T3 10AM 818.7W/MÂ² 28 Â°C 40Â°C 42Â°C 40Â°C 40Â°C 40Â°C 11AM 880.6 31.3Â°C 48Â°C 49Â°C 48Â°C 48Â°C 48Â°C 12AM 997.8 36.2Â°C 58Â°C 60Â°C 59Â°C 58Â°C 58Â°C 1 PM 990 37.2Â°C 70Â°C 71Â°C 70Â°C 70Â°C 70Â°C 2 PM 870.3 35.7Â°C 74Â°C 75Â°C 74Â°C 74Â°C 73Â°C 3 PM 986.4 33.1Â°C 76Â°C 77Â°C 76Â°C 76Â°C 75Â°C 4 PM 1073.2 32.3Â°C 76Â°C 77Â°C 76Â°C 76Â°C 75Â°C
1. EFFICIENCY PARAMETER WITHOUT PCM

Table: 3 Variations of Values without PCM

 PARAMETER SYMBOL VALUE VOLUME V 215litres INITIAL TEMPERATURE Ti 28Â°C HEAT RADIATION Rin 945.28W/mÂ² TIME ELAPSED 1 hr FINAL TEMPERATURE To 76Â°C
2. LATENT HEAT ENERGY

Table: 4 Analysis of Latent Heat Energy

 Time Solar radiation Ta Ti To T1 T2 T3 10 AM 928.6W/mÂ² 28.1 39 41 41 40 40 11 AM 1097.4 31.4 47 49 48 47 47 12NOON 991.2 41 57 60 60 59 59 1 PM 808.3 38.1 68 69
3. EFFICIENCY PARAMETER WITH PCM
 PARAMETER SYMBOL VALUE VOLUME V 215-8.835 =206.165 INITIAL TEMPERATURE Ti 28 HEAT RADIATION Rin 910.58W/mÂ² TIME ELAPSED 1 hr FINAL TEMPERATURE To 78
 PARAMETER SYMBOL VALUE VOLUME V 215-8.835 =206.165 INITIAL TEMPERATURE Ti 28 HEAT RADIATION Rin 910.58W/mÂ² TIME ELAPSED 1 hr FINAL TEMPERATURE To 78

Table: 5 Analysis of Efficiency Parameter with PCM

 S.NO DESCRIPTION VALUE 1 Melting temperature 65Â°C 2 Thermal conductivity (solid) 0.1383 W/mÂ°C 3 Thermal conductivity (liquid) 0.1383 W/mÂ°C 4 Specific heat (solid) 2890 J/kg.K 5 Specific heat (liquid) 2890 J/kg.K 6 Density (solid) 947 kg/m3 7 Density (liquid) 750 kg/m3 8 Latent heat 190 J/kg
5. CALCULATION VOLUME OF THE TANK

VOLUME= AREA* LENGTH

Area (A) = Â¶/4 *D2

V tank= 0.200 mÂ³ (or) 200 litres

VOLUME OF PCM

(

(

= (4/3) Â¶(D/2)3(4) )Â³

3 2

= (4/3) Â¶(0.075/2)3

= 0.22 per single PCM ball TOTAL VOLUME OF THE PCM = 40 *0.22

PCM = 8.83 mm or 8.83 litre SENSIBLE HEAT ENERGY

ENERGY ABSORBED PER ONE HOUR

Q = m Cp (Tf-Tw)

m = 215 litre or 0.215m Cp = 4.18 KJ/kg

Final temp Tf = 40.4Â°C Initial temp Ti =34Â°C

Q = 0.200 4.18 (40.4 -34)

= 5.7516 KJ

HEAT STORAGE PER HOUR IS 5.57516 KJ

In time interval of 12 noon to 1 pm is

= 4.18(70.2-58.6)

= 8.424 KJ

LATENT HEAT ENERGY:

Q = mcp (T1-T2)+m(^H)+Mpcm cp (Tf-Tw)

Volume of with PCM = volume of water tank – volume of PCM

= 200-8.83 = 191.17 litre

Amount of energy storage /hour= 191.17 4.18(68.4 – 59) + (5.2*190)

Q = 8100.84 J + 988 J

Q = 9.088KJ

In time interval of 11 am to 12 noon is

= 191.17 4.19 (68.4 -59) + 5.2(190) + 5.2(2.89)(59-68.9)

= 9.540 KJ

6. RESULT AND DISCUSSION

Fig.6 Comparative Analysis of SHE & LHS

Fig.7 Comparative Analysis of Energy

7. CONCLUSION

Paraffin wax is a good PCM for energy storages in latent heat storages system. It has a suitable storages system. It has a suitable transition temperature range of 28 Â°C to 78

Â°C and relatively high latent heat of 190 KJ/kg. So that sensible heat is 35.11KJ is compare to latent heat energy is 44.724 KJ it is greater than of sensible heat. Comparing with SHE and LTES is 9.614 KJ of energy is excess energy storage.

8. REFERENCE
1. A.S. Ramana, R. Venkatesh, V. Antony Aroul Raj, R. Velraj (2014), Experimental investigation of the LHS system and comparison of the stratication performance with the SHS system using CFD simulationhttp://dx.doi.org/10.1016/ j.solener.2014.02.009 0038-092X/2014 Elsevier Ltd.
2. Dr. C. Dhandapani Study of Squeeze Casting on Metal Matrix Composite – Al-Sic (P) Substance, International Journal of Information And Computing Science (IJICS), Volume 5, Issue 9, 2018.
3. Luisa f.cabeza.( 2015), Advanced in thermal energy storage system, method and application, wood head pulication,pp.185-344
4. Mohamed Fadl*, Philip C. Eames (2019) An experimental investigation of the heat transfer and energy storage characteristics of a compact latent heat thermal energy storage system journal homepage: www.elsevier.com/locate/energy
5. Steven G, Penoncello (2015), Thermal energy system design and analysis CRC press, pp.237 -344
6. Y.B. Tao, Ya-Ling He (2018) A review of phase change material and performance enhancement method for latent heat storage system, https://doi.org/10.1016/j.rser.2018.05.028 Received 9 December 2016; Received in revised form 17 April 2018; Accepted 13 May 2018 Renewable and Sustainable Energy Reviews 93 (2018) 245259 1364-0321/ Â© 2018 Elsevier Ltd.