978-1-4577-1884-7/11/$26.00 ©2011 IEEE

Department of Mechanical Engineering, Department of Mechanical Engineering, Universiti Teknologi Petronas, Universiti Teknologi Petronas,

31750 Bandar Seri Iskandar, Tronoh, Perak. 31750 Bandar Seri Iskandar, Tronoh, Perak. Email: clsaw78@gmail.com Email: hussain_kayiem@petronas.com.my

Abstract – Experimental approach of integrated flat plate solar collector is carried out without PCM. 37 fins are attached below of the absorber plate. PCM is integrated with flat plate collector in this system to enhance the performance. The purpose of fin is to transfer the heat from the absorber plate to any PCM below the absorber plate. Without PCM measurement for the performance is tested during daytime and night time to be compared with reference model. Three values of flow rate and tilt angles have been set to analyses the performance for full day. Combination of 0 degree 4 kg/min produce the highest hot water temperature that is 66 OC. The next day hot water temperature can be maintained at 39 0C. Keywords: PCM; solar; integrated; experimental; ultrasonic

I. INTRODUCTION Solar water heaters are among the workable

application in solar energy system for domestic hot water application. A great portion of them correspond to the so called Integrated Collector Storage Solar Water Heaters (ICSSWH), which they use part of the hot water storage as solar collector described by Gertzos et al. [1]. Cost of construction can be reduced as solar collector and heat storage enclosure are integrated together in one system. This collector can be categorized into two types. First type is the direct configuration in which the storage medium also acts as the energy transfer medium. The second type is the indirect configuration where the energy storage medium and energy transfer medium are separated by a heat exchanger so that heat transfer fluid or hot water is working at atmospheric pressure and not mix together.

Kalogirau [2] examined direct type thermosiphon and target payback time less than 4.5 years. The proposed direct configuration is expected to exhibit higher reliability and life cycle saving.

Many studies have been done to investigate the thermal performance of several type of ICSSWH aiming to improve the system operation. Smyth et al. [3] presented history of evolution of various types of integrated collector storage solar water heater. Most of the reviewed systems use direct heating type, only two use indirect heating. Rabin et al. [4] experimentally investigate the salt-hydrate phase change material integrated solar collector. PCM acts as heat storage

medium to discharge stored energy to flowing cold water through heat transfer medium. De Beijer [4] developed a novel ICSSWH system that incorporates two cylindrical vessel, outer vessel to absorb heat whereas inner vessel is a heat storage medium. Souliotis et al. [5,6] investigate experimentally direct heating with single horizontal cylindrical storage tank inside symmetric CPC type reflector trough. Various cylindrical storage diameters are studied to improve the thermal performance.

Davidson [7] studied transient discharge of two indirect rectangular thermal energy storages, one undivided and another one equally divided storage into two compartments. During the discharge process, the equally divided storage provides higher energy delivery rates and higher heat exchanger outlet temperatures. Arora et al. [8] derives a simple “penalty factor” to study the reduction of the overall solar water heating system efficiency due to usage of heat exchanger. Kumar et al. [9] presented transient analyses of a collection-cum-storage water heater by incorporating the effect of absorber plate as a heat exchanger placed inside the system. Calculations have been made for typical days in Delhi. Henderson et al. [10] try various inclinations to examine both experimentally and numerically by CFD, the performance of a direct heating flat plate ICS. Knudsen et al. [11] investigated the inlet positions of vertical mantle heat exchangers for solar domestic hot water (SDHW) systems experimentally and numerically.

None of the above works examine mechanisms to increase the heat transfer rate in the water circuits (heat transfer intensification). The novelty of the ICSSWH presented here is the use of PCM as a latent heat storage medium and the agitation of the hot water storage via recirculation pump that results in an increase of the heat transfer rate.

In the present work two parameters that affect the efficiency of the examined ICSSWH are investigated:

a) Water flow rates b) Tilt angles

An Investigation of Integrated Flat Plate Solar Collector: Experimental Measurement

Saw C. L. A.P. Dr. Hussain Al-Kayiem.

II. METHODOLOGY

Fig 1: Project’s Methodology

Fig. 1 shows flow of work of experimental measurement. Three values of water mass flow rate and tilt angles have been considered. The outcomes of the experimental work are to measure the temperature of hot water outlet of the solar collector with and without PCM. However, only two (2) flow rates and three tilt angles 00, 100, 200 are considered and experimental work is carried out on without PCM mode.

III. EXPERIMENTAL SET UP The Thermocouples position at the solar collector as

shown in Fig. 2, however the position of thermocouples in the water pipe as shown in Fig. 3. GRAPHTEC data logger is used to capture temperature signal for 24 hours. SHENITEC ultrasonic flow meter is used to measure and control the water flow rate. Ultrasonic approach is used to measure flow rate at any pipe without need to cut any pipe. 0.5 HP pump is used to circulate water so that heat can be harvested all the time.

A) Thermocouples Arrangement There are 23 thermocouples used to measure the

temperature at every position of solar collector system. Average of two (2) thermocouples placed at absorber plate to determine the temperature of absorber plate. Three (3) thermocouples are inserted into the copper pipes to investigate the different temperature at different copper pipes. One (1) thermocouple placed at the back of solar collector to measure the back loss heat. Heat loss from the friction of pump impeller and absorption of materials of impeller is neglected.

Fig. 2: Position of Thermocouples at Solar Collector

Fig. 3: Position of Thermocouples in Water Pipes

TABLE I DESCRIPTION OF THERMOCOUPLES

Solar Collector is placed facing south with latitude 4.50 to capture solar radiation. 100 liters of water is filled in the tank to be circulated through solar collector all time. 100 liters of water is capable to cater six (6) persons in the family.

B. Ultrasonic Measurement Principle

Fig.4: Ultrasonic Measurement Methods

A typical transit-time flow measurement system utilizes two transducers (A and B) that function as both

ultrasonic transmitter and receiver showed in Fig.4. The transducers are clamped on the outside of a closed pipe at a specific distance from each other. The flow meter operates by alternately transmitting and receiving a coded burst of sound energy between the two transducers and measuring the transit time that it takes for sound to travel between the two transducers. The difference in the transit time measured is directly and exactly related to the velocity of the liquid in the pipe.

The transducers can be mounted in three methods, Z-method, V-method and W-method, depending on pipe size. Z-method is used for large pipe. The two transducers are installed on opposite sides of the pipe. V-method is used for medium size pipe. The two transducers are on the same side, thus, the sound transverses the flow twice. W-method is usually used for small pipe. The sound transverses across the flow are four times. In this experiment, V-method is used to measure the water flow rate.

IV. PRELIMINARY RESULT & DISCUSSION In this section, a graph of solar radiation of three (3)

different angles is plotted and two (2) graphs of result at flow rate 4 kg/min and 10 kg/min are plotted.

Three (3) tilting angles that are 00, 100, 200 and 300 are chosen to test the effects of paraffin liquids convection. However, only 00, 100, 200 tilting angle plotted in the preliminary result. Highest solar radiation can be harvested at 00 and also is the reference angle.

Fig.5: Tilting Angle of Solar Radiation

Fig.6: Tilting Angle of Solar Radiation at Different Day

Fig.5 and Fig.6 show that at the angle of 00 and 100, solar radiation collections are maximum compared to other angles. The solar radiations on different days are overlapping as unpredicted solar ray radiate every day. Highest solar radiation measured is more than 700 W/m2.

Fig.7: Output Hot Water at Mass Flow Rate of 4 kg/min: Angle 00

Two values of flow rates are tested instead of three that is 4 kg/min and 10 kg/min. These two values of flow rates are performed at 00, 100, 200 of solar radiation to find the temperature of hot water output.

Fig.7 above shows that 00 angle captured highest solar radiation compare to 100, 200 angle. However, the lower the mass flow rate of water at 00 angles, solar collector can produce higher temperature of hot water than mass flow rate of 10 kg/min at 00 angle.

Fig.8: Output Hot Water at Mass Flow Rate of 10 kg/min: Angle 00

Fig.8 shows that decreased gradually after 4pm as solar radiation decreased. Drop in the solar radiation during afternoon affected the hot temperature produced.

Fig.9: Output Hot Water at Mass Flow Rate of 4 kg/min: Angle 100

Fig.9 shows the hot water produced at the mass flow rate of 4 kg/min. Maximum output of hot water can achieved by this flow rate is 59 0C

Fig.10: Output Hot Water at Mass Flow Rate of 10 kg/min: Angle 100

Fig.10 shows the hot water produced at mass flow rate of 10 kg/min. Maximum output of hot water can be achieved by this flow rate is 66 0C. Comparing the same angle of 100 the hot water produced with different flow rates shows that higher solar radiation rate will influence the hot water produced.

Fig.11: Output Hot Water at Mass Flow Rate of 10 kg/min: Angle 200

Fig.11 shows the hot water produced at the mass flow rate of 10 kg/min. Maximum output of hot water can achieved by this flow rate is 55 0C. This 200 angle produced 50C lower than tilting angle 100.

Fig.12: Output Hot Water at Mass Flow Rate of 4 kg/min: Angle 200

Referring to Fig.12, when the mass flow rate change from 10 kg/min to 4 kg/min at the same tilting angle of 200 the temperature of hot water produced increased to 600.

The results show that lower value of mass flow rates of water inlet gave a significant effect on the hot water output. Combination of 00 tilting angle of solar radiation and 4 kg/min mass flow rate measured 650 temperature of hot water output.

Fig. 13: Output Hot Water at Mass Flow Rate of 4 kg/min: Angle 00

Fig. 14: Output Hot Water at Mass Flow Rate of 4 kg/min: Angle 100

Fig.15: Output Hot Water at Mass Flow Rate of 4 kg/min: Angle 200

Fig.13 – Fig.15 show that air convection temperature on the top of absorber plate is the same under the absorber plate depending on solar radiation. Air in between of absorber plate and double glazing glass is easily heated and collected heat in the morning of the day compared to absorber plate.

Bottom glass temperature increased rapidly during afternoon but it also decreased rapidly at the night. Glass is a poor absorber of solar radiation; glass will absorbs and transmits heat radiation easily. There is a temperature different between inlet pump and inlet tank in the afternoon as water collected heat at absorber plate to warm water in the tank.

However, temperature of water inlet and outlet of tank is same at night and in the early morning.

V. CONCLUSIONS Tilting angle 00 and 100 are the optimum angles of solar

radiation collection. Combination tilting angle of 00 and lowest mass flow rate of water at 4 kg/min gave highest temperature of hot water outlet.

Overnight, temperature of hot water in the tank can still be maintained at 390C for without PCM mode. Insulation play a big roll to reduce heat loss in the tank. After tank is insulated with rock wool, hot water maintained overnight increased from 350C to 390C. Water temperature on the top and bottom of tank is the same from night till morning as no external heat to developed the temperature difference.

ACKNOWLEDGMENT The authors would like to thank the Malaysian

Ministry of Higher Education (MOHE) and University Teknologi Petronas (UTP) for their continuous support in the research work.

REFERENCES [1] Gertzos, K. P., Caouris, Y. G., and Panidis, Th., 2010, “Optimal design

and placement of serpentine heat exchangers for indirect heat withdrawal, inside flat plate Integrated Collector Storage Solar Water Heaters (ICSSWH),” Renewable Energy, 35, pp. 1741 – 1750.

[2] Kalogirou, S., 2009, “Thermal performance, economic and environmental life cycle analysis of thermosiphon solar water heaters,” Solar Energy, 83, pp. 39-48.

[3] Smyth, M., Eames, P. C., and Norton, B., 2006, “Integrated Collector Storage Solar Water Heaters,” Renewable and Sustainable Energy Reviews, 10, pp. 503-538.

[4] Rabin, Y., Bar-Niv, I., Korin, E., and Mikkie, B., 1995, “Integrated solar collector storage system based on a salt-hydrate phase-change material,” Solar Energy, 55, pp. 435-444.

[5] Souliotis, M., and Tripanagnostopoulos, Y., 2004, “Experimental study of CPC type ICS Solar Systems,” Solar Energy, 76, pp. 389-408.

[6] Tripanagnostopoulos, Y., and Souliotis, M., 2008, “Study of the distribution of the absorbed solar radiation on the performance of a CPC-type ICS water heater,” Renewable Energy, 33, pp. 846-858.

[7] Davidson, J. H., and Ragoonanan, V., 2005, “Divided storage in an indirect integral collector storage with immersed heat exchanger,” Proceedings of ISEC2005, 2005 International Solar Energy Conference.

[8] Arora, S., Davidson, J., Burch, J., and Mantell, S., 2001, “Thermal penalty of an immersed heat exchanger in integral collectors storage systems,” Journal of Solar Energy Engineering, 121, pp. 180-186.

[9] Kumar, A., and Tiwari, G. N., 1988, “Transient analysis of collector –cum-storage water heater integrated with heat exchanger,” Energy Conversion and Management, 28, pp. 201-206.

[10] Henderson, D., Junaidi, H., Muneer, T., and Grassie, T., 2007, “Experimental and CFD Investigation of an ICSSWH at various inclination,” Renewable and Sustainable Energy Reviews, 11, pp. 1087-1116.

[11] Knudssen, F., and Furbo, S., 2004, “Thermal stratification in vertical mantle heat exchangers with application to solar domestic hot-water system,” Applied Energy, 78, pp. 257-272.