Solar energy based thermal energy storage system using phase ...

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In the present system solar energy is used as heat source to store the thermal energy in the form of sensible heat and latent heat. In the TES system paraffin and ...
Int. J. Renewable Energy Technology, Vol. 3, No. 1, 2012

Solar energy based thermal energy storage system using phase change materials R. Meenakshi Reddy* Department of Mechanical Engineering, Sri Venkateswara College of Engineering and Technology, Chittoor, Andra Pradesh, 517127, India E-mail: [email protected] *Corresponding author

N. Nallusamy Department of Mechanical Engineering, Sri Venkateswara College of Engineering, Post Bag No. 3, Pennalur, Sriperumbudur Tamil Nadu, 602 105, India E-mail: [email protected]

T. Hariprasad Department of Mechanical Engineering, Sri Venkateswara College of Engineering and Technology, Chittoor, Andra Pradesh, 517127, India E-mail: [email protected]

K. Hemachandra Reddy JNTU College of Engineering, Anantapur, Andra Pradesh, 515002, India E-mail: [email protected]

G. Ramachandra Reddy Malla Reddy College of Engg. for Women, Suraram ‘X’ Road, Quthubullapur Municipality, Hyderabad, India E-mail: [email protected] Abstract: Nowadays for solar heating applications, usage of phase change materials (PCM) to store the heat in the form of latent heat is increased, because large quantity of thermal energy is stored in small volume. The present experimental investigation on the thermal energy storage (TES) system is developed using paraffin and stearic acid as PCM. In the present system solar energy is used as heat source to store the thermal energy in the form of sensible heat and latent heat. In the TES system paraffin and stearic acid are stored in the form of spherical capsules of 38 mm diameter. Investigation results related to the charging time and recovery of stored energy are presented. The experimental investigation showed that the charging and recovery of storage Copyright © 2012 Inderscience Enterprises Ltd.

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R.M. Reddy et al. energy are less affected by the PCM materials (paraffin and stearic acid). But, utilisation of stearic acid as PCM is more economical without affecting the quantity of thermal energy stored, charging time and recovery of the stored thermal energy. Keywords: heat transfer fluid; HTF; paraffin; phase change material; PCM; stearic acid; thermal energy storage; TES. Reference to this paper should be made as follows: Reddy, R.M., Nallusamy, N., Hariprasad, T., Reddy, K.H. and Reddy, G.R. (2012) ‘Solar energy based thermal energy storage system using phase change materials’, Int. J. Renewable Energy Technology, Vol. 3, No. 1, pp.11–23. Biographical notes: R. Meenakshi Reddy received his BTech in Mechanical Engineering from Dr. BAM University, Maharashtra, India, in 1997 and his MTech in Energy Systems Engineering from VT University, Karnataka, India, in 2001. He is currently an Associate Professor in the Department of Mechanical Engineering, Sri Venkateswara College of Engineering & Technology, Chittoor, India. His research interests are in the areas of solar energy, simulation of heat and mass transfer systems, CFD and renewable energy sources. He has published more than 15 papers in national, international conferences and journals. He is a life member of ISTE. N. Nallusamy received his BE in Mechanical Engineering from Bharathiar University, in India, in 1992, his ME in Thermal Power Engineering from Annamalai University, India in 1995 and his PhD in Renewable Energy Sources from Anna University, India in 2007. He is currently Professor and Head of the Department of Mechanical Engineering, Sri Venkateswara College of Engineering, Sriperumbudur, India. His research interests are in the areas renewable energy sources (solar energy and applications), thermal energy storage systems – heat and cool storage for domestic and industrial applications, heat transfer analysis and energy conservation and bio-fuels for stationary and automotive engines. He has published more than 24 papers in national, international conferences and journals. He is a life member of ISTE, India and in Solar Energy Society of India (SESI) and a member of Society of Automotive Engineers (SAE) India. T. Hariprasad received his BTech in Mechanical Engineering from JNT University, Hyderabad, India, in 2000 and his MTech in Thermal Engineering from JNT University, Hyderabad, India, in 2005. He is currently an Associate Professor in the Department of Mechanical Engineering, Sri Venkateswara College of Engineering & Technology, Chittoor, India. His research interests are in the areas of alternative fuels, simulation of heat and mass transfer systems, CFD and renewable energy sources. He has published more than 15 papers in national and international conferences. He is a life member of ISTE, India and Combustion Institute of Indian section. K. Hemachandra Reddy received his BE in Mechanical Engineering from SVU, Tirupati, India, his MTech in Heat Power Engg. and his PhD in I.C. Engines from JNT University, Hyderabad, India. He has a rich experience in the field of mechanical engineering in different cadres as an Assistant Professor, Professor and Principal. He is currently the Director of Academic and Planning, JNT University, Anantapur, India. His research interests are in the areas of alternative fuels, simulation of heat and mass transfer systems, combustion in gas turbines, thermodynamics, CFD and renewable energy sources. He has published more than a hundred papers in refereed journals and more than 25 papers in national and international conferences. He is a life member of ISTE.

Solar energy based thermal energy storage system

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G. Rama Chandra Reddy received his BE in Mechanical Engineering from SVU, Tirupati, India in 1985, his MTech in Industrial Metallurgy from NIT, Warangal, India in 1987, and his PhD in Composite Materials from SK University, Anantapur, India in 2000. He has a rich experience in the field of mechanical engineering in different cadres as an Assistant Professor, Professor and Principal. He is currently the Principal of Malla Reddy College of Engineering for Women, India. His research interests are in the areas of production engineering, engineering metallurgy, welding technology, foundry technology and metrology and technology. He has published more than 20 papers in refereed journals and more than ten papers in national and international conferences. He is a life member of ISTE.

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Introduction

The effective use of solar energy is hindered by the intermittent nature of its availability, limiting its use and effectiveness in domestic applications, notably, water heating. Latent heat thermal energy storage (LHTES) system using phase change materials (PCMs) as a storage medium offers advantages such as high heat storage capacity, small unit size and isothermal behaviour during charging and discharging compared to the sensible heat storage system (SHS). However, LHTES systems are not in commercial use due to poor heat transfer rates during heat storage and recovery process. The efforts are ongoing to overcome this problem. Cho and Choi (2000) investigated the thermal characteristics of paraffin in a spherical capsule during freezing and melting processes. Experiments were performed with paraffin. Nallusamy (2003) studied effective utilisation of solar energy for water heating applications using combined sensible heat and latent heat storage system. Fouda et al. (1984) studied the characteristics of Glauber’s salt as the PCM in the solar storage system. The effect of several variables was observed over many complete cycles of the unit, including variable HTF flow rate and inlet temperature, wall thickness, etc. Mehling et al. (2003) presented experimental and numerical simulation results of energy storage density of solar hot water system using different cylindrical PCM modules. Results showed that adding PCM modules at the top of the water tank would give the system of higher storage density and compensate heat loss in the top layer. Thermal performance of LHTES systems integrated with solar heating systems was also investigated by Ghoneim et al. (1989), Hoogendoorn and Bart (1992) and Bansal and Buddhi (1992). Later, Ettouney et al. (2006) studied the performance of thermal energy storage (TES) system filling paraffin wax and metal beads in spherical capsules. He has shown that the heat transfer rate is increased because of placing the metal beads along with the paraffin in the capsules. The objective of the present work is to predict the suitable PCM among paraffin and stearic acid for sensible and LHTES unit integrated with varying (solar) heat source. Different PCMs of the high density poly ethylene (HDPE) spherical capsules were used which are surrounded by a SHS material/water. Parametric studies are carried out to examine the effects of the PCM and HTF flow rates on the performance of the storage unit for varying inlet fluid temperatures. The experiments were carried out for both energy storage and recovery periods using water as heat transfer fluid (HTF).

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Experimental investigations

A schematic diagram of the experimental setup is shown in Figure 1. This consists of an insulated cylindrical TES tank, which contains PCM encapsulated spherical capsules, solar flat plate collector, flow meter and circulations pump. The stainless steel tank has a capacity of 51 litres (360 mm diameter and 504 mm height) to supply hot water for a family of 5 to 6 persons. There are two plenum chambers on the top and the bottom of the tank and a flow distributor is provided on the top of the tank to make uniform flow of HTF. The storage tank is insulated with glass wool of 50 mm thick. The outer diameter of spherical capsule is 38mm and it is made of HDPE with wall thickness of 1.00 mm. The total number of capsules in storage tank in case of paraffin and stearic acid are 870 and 836 respectively to store the 10,000 KJ of heat. The spherical capsules are uniformly packed in layers and each layer is supported by wire mesh. The paraffin is used as PCM that has a melting temperature of 61 ± 2°C and latent heat of fusion of 213 KJ/Kg. Water is used as both SHS material and HTF. Stearic acid is used as another PCM that has a melting temperature of 57 ± 1°C and latent heat of fusion of 198 KJ/Kg. A flow meter with accuracy of ±2% is used to measure the flow rate of HTF and a centrifugal pump (100 L/min) is employed to circulate the HTF through the storage tank. The TES tank is divided into four segments i.e., at x/L = 0.25, 0.5, 0.75 and 1.0 (L is length of the TES tank, mm; x is the axial distance from the top of the TES tank, mm; x/L is the dimension less axial distance from the top of the TES tank) along its axial direction and the RTDs with an accuracy of ±0.3°C are placed at the inlet, outlet and four segments of the TES tank to measure the temperatures of HTF. Another four numbers of RTDs are inserted into the PCM capsules and they are placed at four segments of the TES tank to measure the temperatures of PCM. The position and number of RTDs are also designated in Figure 1. The RTDs are connected to a temperature indicator, which provides instantaneous digital outputs. (The setup is placed in Chittoor town, Latitude 13° 13’ N and Longitude 79° 08’ E, Andhra Pradesh, India.) The TES tank is connected with 2m2 active solar flat plate collector heat source (for solar irradiation data see Annexure) and the PCM capsules in the TES tank are surrounded by water. Several experiments are conducted with different flow rates of HTF. During the charging process the HTF is circulated through the TES tank continuously. The HTF exchanges its energy to PCM capsules and at the beginning of the charging process, the temperature of the PCM inside the packed bed capsules is 32°C, which is lower than the melting temperature. Initially the energy is stored inside the capsule as sensible heat until the PCM reaches its melting temperature. As the charging process proceeds, energy storage is achieved by melting the PCM at a constant temperature. As the charging process proceeds, energy storage is achieved by melting the PCM at a constant temperature. Finally, the PCM becomes superheated. The energy is then stored as sensible heat in liquid PCM. Temperature of the PCM and HTF at different locations of the TES tank as shown in Figure 1 are recorded at an interval of 12 minutes. The charging process is continued until the PCM temperature reaches the value of 70°C.

Solar energy based thermal energy storage system Figure 1

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Schematic of experimental set-up

Note: 1 – solar flat plate collector; 2 – pump; 3 and 4 – flow control valves; 5 – flow meter; 6– TES tank; 7 – PCM capsules; 8 – temperature indicator; Tp and Tf – temperature sensors (RTDs) Figure 2

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Photograph of TES tank and solar collector (see online version for colours)

Results and discussion

The temperature distributions of HTF and the PCMs in the storage tank for different mass flow rates are recorded during charging and discharging processes.

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3.1 Charging process The temperature distribution of HTF and PCM at four segments of the TES tank, i.e., at x/L = 0.25, 0.5, 0.75 and 1.0 is shown in Figures3a and 3b (L is length of the TES tank, mm; x is axial distance from the top of the TES tank, mm; x/L is the dimensionless axial distance from the top of the TES tank). Figure 3a represents the temperature variation of PCM during the charging process for mass flow rate of 2 L/min and paraffin as PCM. It is seen from the figure that the PCM temperature (Tp) increases gradually at the beginning of the charging period, remains nearly constant around 61°C during melting process and increases sharply during heating of liquid PCM. The PCM in the first segment (x/L = 0.25) is completely charged, with 72% of the total charging time. This charging process is terminated when the PCM temperature in all segments reaches 70°C. Figure 3b represents the temperature variation of the HTF inside the storage tank for mass flow rate of 2 L/min and paraffin. It is observed from Figure 3b that the temperature of the HTF at all segments increases gradually until it reaches the temperature of 62°C or 63°C and then remains nearly constant around 65°C for a period of 48 minutes during which the PCM undergoes phase change at 61 ± 1°C. Consequently HTF temperature (Tf) increases up to 72°C. It is also observed from Figure 3a and 3b that there is no significant temperature difference between the segments from top to bottom of the storage tank during the sensible heating of the solid PCM and also during phase change period. The reason is that the water temperature in the storage tank increases gradually in accordance with HTF inlet temperature (Tfi) supplied from the solar collector and that the PCM temperature also increases gradually along with HTF temperature. From the temperature histories it is inferred that in the present system, the heat transfer rate possible from the HTF to the PCM in the storage tank is higher than the heat-receiving rate of HTF from the solar collector. Hence, it is possible to reduce the charging time further by increasing solar collector surface area.

3.1.1 Temperature histories of HTF and PCM Figure 3c shows the variation of both HTF and PCM temperatures at segment 2 (x/L = 0.5) with HTF inlet temperature. The instantaneous amount of heat transfer to the PCM depends on the temperature difference prevailing between HTF and PCM at a given time. During sensible heating of solid PCM, the temperature of both HTF and PCM increases at a faster rate and the temperature difference between them also increase continuously until the PCM reaches its melting temperature 61 ± 1°C. The increase in temperature is higher in water than in the PCM as a more quantity of heat is absorbed by the water than the amount of heat it gives to the PCM. This is due to the higher resistance offered by the solid PCM for heat flow. A stage is reached when the entire heat in the HTF is transferred to PCM by convection. Hence, beyond this stage, HTF temperature also remains nearly constant. After the completion of the melting process, the HTF and PCM temperatures further increase and the charging process is continued until the PCM attains 70°C.

Solar energy based thermal energy storage system Figure 3

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Temperature histories during charging process (m = 2 L/min; paraffin): (a) PCM; (b) HTF; (c) HTF and PCM (see online version for colours)

PCM Temp. in Degree Centigrade

75 70 65 60 Tp4;x/L=1.0

55

Tp3; x/L=0.75

50

Tp2; x/L=0.5

45

Tp1; x/L=0.25

40 35

168

156

144

132

120

96

108

84

72

60

48

36

24

12

0

30

Time(min)

75 70 65 60

Tf1; x/L=0.25

55 50

Tf2; x/L=0.5

45

Tf4; x/L=1.0

Tf3; x/L=0.75

40 35 168

156

144

132

120

108

96

84

72

60

48

36

24

12

30 0

HTF Temp. in Degree Centigrade

(a)

Time(min)

(b) 80

Temp.inDegree Centigrade

70

60 Tf i (HTF inlet) Tf 2; x/L=0.5 Tp2; x/L=0.5

50

40

168

156

144

132

120

108

96

84

72

60

48

36

24

12

0

30

Time (min)

(c)

3.1.2 Effect of HTF flow rate Figure 4 illustrates the effect of varying the mass flow rate of HTF (2, 4, and 6 kg/min) during the charging of the storage tank for the varying HTF inlet. Mass flow rate has

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significant effect on charging time. It is seen from the figure that the charging time is decreased by 24% when the mass flow rate is increased from 2 to 6 kg/min. This is because the water temperature in the storage tank increases gradually in accordance with inlet temperature of HTF supplied from the solar collector and the PCM temperature also increases gradually along with HTF temperature. Hence, the temperature potential difference between the HTF and PCM is small for the heat transfer and the mass flow rate has more significance on the rate of heat transfer. It is seen from the figure that the time taken for rising the melting temperature of PCM material is around 25% to 30% of the total time of charging. The time taken for melting the PCM material is around 45% to 50%, the time taken to rise above the melting temperature is around 15% to 20%. Figure 4

Effect of mass flow rate of HTF on charging time for varying HTF inlet temperature (see online version for colours)

65 60 55

m=2 L /min

50

m=4 L /min

45

m=6 L /min

40 35 168

156

144

132

120

96

108

84

72

60

48

36

24

0

30 12

PCM Tem p. in Degree Centigrade

70

Time (min)

3.1.3 Effect of PCMs on charging time Figure 5 shows the curves for paraffin and stearic acid PCMs. The charging time of stearic acid is 11% to 13% less when compared to the paraffin. This is because of latent heat, thermal conductivity and specific heat quantities for both PCMs are 5% to 7% variation.

80 70 60

Paraffin;x/L=1.0 Stearic Acid;x/L=1.0

50 40

Time (min)

170

158

146

134

122

110

98

86

74

62

50

38

26

14

30 2

P C M Te m p. in D e gre e C e ntigra de

Effect of PCMs on charging time for varying HTF inlet temperature (see online version for colours)

-1 0

Figure 5

Solar energy based thermal energy storage system

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3.2 Discharging process Discharging experiments are conducted in batch wise process. After TES tank is charged fully (i.e., 70°C in all segments of TES system). Cold water (32°C) is sent to the TES tank with a constant mass flow rate of 2 L/min. Each batch of 20 litres of hot water is withdrawn from the tank at a flow rate of 2/4/6 L/min. The retention time between batches is set at 20 minutes. This process is continued till the average temperature of the batches collected would reach 45 ± 1°C (This temperature is considerable as a comfortable bath tub temperature in India). During the discharging process the temperatures of HTF and PCM at various levels of the tank are noted at fixed intervals of time.

3.2.1 Effect of flow rate, paraffin as PCM Figures 6 and 7 show the batches of water collected Vs temperature. The temperature of water discharged decreases gradually from 64°C to 34°C. It shows that the temperature of water collected at 2 L/min is less than the temperature of water collected at 6 L/min. Higher outlet temperature of water is achieved at a withdrawal rate of 6 L/min due to the time given for mixing of cold water is less. Figure 6

Variation of out put (L) for different flow rates (see online version for colours) 65

O u tlet T em p . ( 0 C )

60 55 2 L/min

50

4 L/min

45

6 L/min

40 35

8

7

6

5

4

3

2

1

0

30 Batch

Variation of out put (L) for different flow rates (see online version for colours) 65 60 55 2 L/min

50

4 L/min

45

6 L/min

40 35

Batch

8

7

6

5

4

3

2

1

30 0

O u tlet T em p .( 0 C )

Figure 7

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It is also observed from the Figure 6 that a total of 156 lit of water is collected (before the outlet temperature drops to 34°C) at 2 L/min and it is 130 lit at 6 L/min. The average temperature of water withdrawn is 45°C at 2 L/min and it is 46.5°C at 6 L/min. Hence, it may be concluded that water collected at 2 L/min is able extract more thermal energy from the TES tank compared to other rates. This is because for collecting 20 litres, ten minutes is needed at 2 L/min and at 6 L/min it needs only 3.5 minutes.

3.2.2 Effect of flow rate, stearic as PCM Figure 7 shows the same as Figure 6 shows. The out put of stearic acid PCM is 4% to 5% less for different flow rates. This is because of stearic acid has 7% less latent heat of fusion of paraffin.

3.2.3 Effect of PCM material In Figure 8, the curves of paraffin and stearic acid PCM shows that the average temperature of batch wise discharged water is almost same. The quantity of water discharged is also almost same with slight variation of 3% to 4%. This is because of latent heat, thermal conductivity and specific heat quantities for both PCMs are almost same with 5% to 7% variation. Figure 8

Variation of out let (lit) for the different PCMs the flow rate of 2 L/min (see online version for colours)

O u t  L et  T em p .  in   D eg ree  C en tig rad e

70 65 60 55 50

P araffin

45

S tearic

40 35

HDP E , 38 mm Dia.,2lit/min 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160

30 Out P ut (lit)

3.3 Comparison of TES (SHS+LHS) system and SHS system The charging and discharging process performance of TES system is compared with SHS system of same capacity (volume) storage tank. Details of energy stored and discharged are given in Table 1. Details of TES system experiment taken for comparison: spherical capsules diameter = 38 mm, Discharge flow rate = 2 L/min. Details of SHS system experiment: discharge flow rate = 2 L/min.

Solar energy based thermal energy storage system Table 1

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Comparison of TES system and SHS system charging and discharging processes

Status of description

TES (SHS + LHS)

SHS

0.051

0.051

Total volume of the TES tank (m3) Total hot water withdrawn (total hot water average temp. is 43 ± 2°C)

156 L

113 L

Time between batches

10 min

10 min

Initial temperature of water and PCM in the TES tank is 32°C (reference) KJ

Energy stored (KJ) 0

0

Temperature of water and PCM at 61°C (melting temperature) SHS

3,982.28

--

After completion of PCM melting process

4,260.00

--

Temperature of water at 70°C

903.0

8,100.0

Temperature of PCM at 70°C

429.0

--

Energy stored in the capsule material

425

--

Total heat stored

10,000

8,100.0

Heat recovered from the system in the form of hot water during discharge

7,173.0

5,195.0

422.0

--

After discharge the heat stored in the TES tank (water = 34°C and PCM = 38°C) After discharge the heat stored in the SHS tank at 38°C Un accounted heat losses

--

1,279

2,405.0

1,625

3.4 Uncertainty analysis The results of uncertainty analysis are tabulated in the Table 2. Table 2

Summary of estimated uncertainties

Parameters

Uncertainty (%)

Temperature

0.47

Length

0.10

Diameter

0.052

Time

0.33

Flow Rate

0.83

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Conclusions

A TES system has been developed for the use of hot water at an average temperature of 45°C ± 1 for domestic applications using combined sensible and latent heat storage concept. Mass flow rate has significant effect on charging time. It is seen from the figure that the charging time is decreased by 24% when the mass flow rate is increased from 2 to 6 L/min.

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The quantity of water discharged is also almost same in paraffin and stearic acid, with slight variation of 3% to 4%. This is because of latent heat, thermal conductivity and specific heat quantities for both PCMs are almost same with 5% to 7% variation. But the cost of stearic acid is around Rs.48 per kg where as paraffin cost is Rs.75 in the Indian market. In economical point of view the stearic acid gives the same output at less initial cost. Hence, stearic acid is the best alternate for TES system.

References Bansal, N.K. and Buddhi, D. (1992) ‘Performance equation of a collector cum storage using phase change materials’, Solar Energy, Vol. 48, No. 3, pp.185–194. Cho, K. and Choi, S.H. (2000) ‘Thermal characteristics of paraffin in a spherical capsule during freeing and melting processes’, Int. J. Heat and Mass Transfer, Vol. 43, pp.3183–3196. Ettouney, H., Alatiqi, I., Al-Sahali, M. and Al-Hajirie, K. (2006) ‘Heat transfer enhancement in energy storage in spherical capsules filled with paraffin wax and metal beads’, Energy Conversion and Management, Vol. 47, No. 2, pp.211–228. Fouda, A.E., Despault, G.J.G., Taylor, J.B. and Capes, C.E. (1984) ‘Solarstorage systems using salt hydrate latent heat and direct contact heat exchange-II characteristics of pilot system operating with sodium sulphate solution’, Solar Energy, Vol. 32, No.1, pp.57–65. Ghoneim, A.A. and Klein, S.A. (1989) ‘The effect of phase-change material properties on the performance of solar air-based heating systems’, Solar Energy, Vol. 42, No. 6, pp.441–447. Hoogendoorn, C.J. and Bart, G.C.J. (1992) ‘Performance and modeling of latent heat stores’, Solar Energy, Vol. 48, No. 1, pp.53–58. Mehling, H., Cabeza, L.F., Hippeli, S. and Hiebler, S. (2003) ‘PCM-module to improve hot water heat stores with stratification’, Renewable Energy, Vol. 28, No. 5, pp.699–711. Nallusamy, N. (2003) ‘Effective utilization of solar energy for water heating applications using combined sensible and latent heat storage system’, Proc. of the International Conference on New Millennium Alternate Energy Solutions for Sustainable Development, PSG Tech, pp.103–108.

Nomenclature PCM

Phase change material

TES

Thermal energy storage

HTF

Heat transfer fluid

SHS

Sensible heat storage

LHTES

Latent heat thermal energy storage

HDPE

High density poly ethylene

RTD

Resistance temperature detectors

Solar energy based thermal energy storage system

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Annexure Table 3 Time

Data of solar irradiance and ambient temperature T atm.

Day 1

T atm.

Day 2

T atm.

Day 3

T atm.

Day 4

38.0

893.65

38.0

908.42

38.5

937.96

41.5

1,011.82

39.5

967.50

41.5

1,011.82

41.0

982.27

42.0

1,026.59

41.0

982.27

41.0

997.05

40.0

974.89

41.0

997.05

37.5

893.65

39.0

952.73

35.0

827.18

39.5

960.12

10.30

34

812.41

35.5

841.95

10.45

34.5

827.18

37.0

871.49

11.00

34.3

812.41

37.5

901.03

11.15

34.5

827.18

38.0

908.42

11.30

35

834.56

38.5

930.58

11.45

35.4

849.34

39.0

952.73

12.00

36.5

860.34

39.0

952.73

12.15

40.0

974.89

40.0

974.89

12.30

39.0

915.81

39.0

952.73

12.45

38.0

812.41

39.0

952.73

13.00

40.0

974.89

39.5

965.24

13.15

39.5

952.73

40.0

970.23

13.30

41.0

975.21

38.5

937.24

13.45

38.0

937.96

38.0

915.81

14.00

36.5

859.34

38.0

908.42