Experimental study on performance of square tube absorber with phase change material

The intermittent nature of solar radiation has decreased the performance efficiency of solar heaters. Integrating the solar heater with thermal energy storage component could increase its performance effectively. In this article, an investigation on the effect of phase change material (PCM) as the thermal energy storage component on the performance of square aluminum tube was carried out experimentally. In the first phase, the temperature behavior of square aluminum tube with two types of PCM, namely, generic plant‐based PCM (A2) and paraffin wax (A3), was compared with square aluminum tube without PCM (A1). In the second phase, the performance of square aluminum tube was investigated with different paraffin wax masses of 38 g (B1), 48 g (B2), and 58 g (B3). Based on the result, the A3 tube configuration performed better than A1 and A2 tube configurations with higher heat gain rate (0.08°C/s) and lower heat discharge rate (−0.04°C/s). The B2 tube configuration was found to have maximum heat gain of 3.73 kJ with higher heat discharge rate as compared with other square tube configurations. The average temperature difference between internal and external surface tube of B2 was lower (4.3°C) leading to higher average temperature difference at ambient temperature of 25.3°C. Instantaneous efficiency of the tube B2 is higher than the B1 and B3 tube configurations by 16% and 26%, respectively. The result suggests that the insertion of paraffin wax inside the square absorber tube improves the temperature response of the absorber in the situation of intermittent solar radiation

Performance of force circulation cross-matrix absorber solar heater integrated with latent heat energy storage material

The utilization of thermal energy storage in the thermal absorber applications has been increasingly important especially in the application where there is a mismatch between energy demand and energy supply. This technology implies that the heat is stored during charging or discharging process through melting and freezing of the thermal energy storage material so that it can be used in the future. This paper presents the outcome of the experimental investigation on the performance of cross-matrix absorber (CMA) utilizing paraffin as the thermal energy storage material. Experiments were carried out by exposing the CMA under different artificial solar radiation (300 W/m2, 500 W/m2, 700 W/m2 and 900 W/m2) for 30 minutes followed by 30 minutes of discharging process. Based on the observation, it was found that smaller mass flow rate value of 0.005 kg/s gave the highest temperature output regardless of the intensity of solar radiation as compared to the other after 30 minutes of charging process. In terms of heat gain by the thermal absorber, it was concluded that the highest mass flow rate of 0.01 kg/s passing through the absorber lead to the higher heat gain by the CMA, hence prolonged the cooling down / discharging period as shows by the result, where case with maximum mass flow rate (0.01 kg/s) consistently contributed to the higher heat gain by the absorber. This feature is very useful in the solar thermal collector related applications such as crop drying and domestic building heating. The heat gain by the absorber is also contributed by the intensity of the solar radiation

A performance and technoeconomic study of different geometrical designs of compact single-pass cross-matrix solar air collector with square-tube absorbers

This manuscript presents a performance study on a forced convection single-pass solar air heater channel with compact cross-matrix absorber (CMA) incorporating metal hollow square-tube absorbers. Four different geometries of CMA (Type I, II, III and IV) were investigated experimentally to evaluate their efficiency, pressure drops and heat transfer parameters. The experiments were conducted with uniform heat flux (indoor) and outdoor solar radiation as heat source. The air mass flow rates used were between 0.0142 kg/s and 0.0360 kg/s. Techno-economic feasibility studies were conducted using cost-benefit ratio (AC/AEG) method. Thermal efficiency of the CMA obtained by Type I with 76%, being the highest. CMA Type I also exhibited the highest temperature elevation than other configurations with 15.3 °C and thermal capacity of 38.7 kJ. Maximum pressure drop obtained was 1.33 Pa in turbulent condition with Reynolds number of 50,794. Type I has the advantage of high performance CMA and has comparatively lower cost-benefit ratio (AC/AEG) of 0.15 RM/kWh than other type of thermal absorbers. © 2018 Elsevier Lt

Performance analysis of flat plate base-thermal cell absorber (FPBTCA): low thickness design

Research to improve flat plate solar collector performance such as design and material used continuously developed. This paper's objective is to analyze the performance of the thermal cell absorber attached to a flat plate absorber collector (FPBTCA) through a low thickness design. It will produce a lightweight and portable collector application with efficient temperature conversion duration and has energy storage ability. Stainless steel and aluminum materials with different thicknesses use as thermal cell absorbers then aluminum materials use as a flat plate absorber base-collector. The experiment performs using a solar simulator with solar radiation of 700 W/m2. Referring to the results in term of heat storage (Qstorage), the heat transfer rate of the collector (Q ̇) and efficiency of the collector shows that stainless steel 1.0 mm with an aluminum base absorber (Case E) has a higher value which is 412 kJ, 18.21 kW, and 47.08 %, respectively. The higher total energy gain collected at the bottom plate as dummy load in the drying chamber (T1 and T2) is stainless steel 1.0 mm with an aluminum absorber base-collector (Case E) value of 2.85 kJ. Stainless steel 1.0 mm with an aluminum absorber base-collector (Case E) has the maximum value of energy gain at 300 seconds which is 116.08 J for the bottom plate (T1 and Ta). Flat plate base absorber thermal cell (FPBTCA CASE E) shows better performance in thermal storage than Flat Plate Solar Collector (FPSC)

Investigation on the thermal performance of evacuated glass-thermal absorber tube collector (EGATC) for air heating application

Existing design of Heat-Pipe Evacuated Tube Collector (HP ETC) for water heating require storage tank while additional heat exchanger require for air heating application which leads to the extra spacing and costing. HP ETC also need to be tilt at the correct angle to optimize the system performance. Furthermore, the installation also needs to be positioned either to south or north facing to ensure the maximum absorption of energy. These could lead to the design limitation. The aim of this research is to investigate on the thermal performance of Evacuated Glass-Thermal Absorber Tube Collector (EGATC) for air heating application. EGATC was developed from conventional Evacuated Tube Collector (ETC) and the comparative result between HP ETC performance were evaluated. The three days outdoor experimental results show EGATC (Day 1: 50.9 °C, Day 2: 53.9 °C, Day 3: 49.2 °C) performed better with slightly higher temperature at outlet temperature compare with HP ETC (Day 1: 46.7 °C, Day 2: 50.3 °C, Day 3: 46.9 °C). It is concluded that EGATC have better performance in term of temperature different and outlet temperature as compared to HP ETC. EGATC (Day 1: 53.6%, Day 2: 50.6%, Day 3: 49.8%) also have greater efficiency in term of heat storage capability as compared to HP ETC (Day 1: 42.7%, Day 2: 41.6%, Day 3: 41.1%). Regarding energy buffer storage, EGATC have better energy storage compared to HP ETC at sudden weather change such as clouds. The outlet temperature of EGATC (42.3 °C) was remained slightly higher compared to HP ETC (39.9 °C) at the beginning. The outlet temperature gradually drops slower during discharging period until the end of the experiment for 15 minutes towards outlet temperature 41.1 °C and 37.2 °C for both EGATC and HP ETC with temperature difference 1.2 °C and 2.7 °C respectively

Study on selection of a suitable material and the parameters for designing a portable flat plate base-thermal cell absorber (FPBTCA)

Several types of flat plate solar collectors have been designed and developed with various technical parameters involved in the design. The inappropriate flat plate solar collector parameter design and material chosen will affect its performance. Investigation on the effect of flat plate absorber collector material, glass thickness, air gap distance, thermal cell absorber thickness, and flat plate absorber base collector thickness on the performance of solar thermal collectors was conducted in this work. The experiment was performed using the solar simulator with solar radiation of 450 and 750 W/m2. The flat plate absorber collector materials used in this experiment were stainless steel 304 and aluminum. The glass thickness used in this experiment was 2.0, 3.0, 4.0, 5.0, and 10.0 mm. The air gap between the flat plate absorber and glass used in this experiment was 0, 5.0, 10.0, 20.0, and 30.0 mm. The stainless steel thermal cell absorber thickness applied in this experiment was 0.5, 1.0, and 2.0 mm. Meanwhile, the aluminum flat plate base absorber base collector thickness was 0.5, 0.8, and 1.0 mm. The results showed that the 2.0 mm glass thickness has the maximum flat plate absorber temperature (88.1 oC at t = 600 s), high heat gain rate (0.097 oC/s), and the highest total heat gain (1207.33 J). The results also revealed that the air gap distance of 10 mm achieved the maximum flat plate absorber temperature (64.6 oC at t = 600 s), the highest heat gain rate (0.058 oC/s), and the highest total heat gain (4750.92 J). The stainless steel thermal cell absorber thickness of 1.0 mm has the thermal cell absorber temperature of 76.2 oC at t = 600 s and a high heat gain rate at 0.08 oC/s. The aluminum flat plate base absorber achieved the highest flat plate absorber temperature (67.2 oC at t = 600 s) and the highest heat gain rate (0.062 oC/s). By using double glass as glass cover increase the flat plate absorber temperature (76.3 oC at t = 600 s) and the highest heat gain rate (0.077 oC/s). This research aims to produce a flat plate absorber with better energy storage, i.e., the performance of the stainless steel plate absorber is better than aluminum with the same thickness. Although the stainless steel flat plate absorber collector showed a lower temperature than aluminum, it has a higher temperature drop than the latter

Hydrodynamics investigations of kaffir lime leaves drying in a swirling solar drying chamber with inclined slotted angle air distributor

The present work aims to investigate the behavior of drying kaffir lime leaves in a swirling solar drying chamber (S-SDC) fitted with an inclined slotted angle air distributor. A distributor plated with inclined slotted angle was located at the air inlet at the bottom of the chamber. Experimental and numerical methods have been applied to analyze the efficiency of developed S-SDC assisted solar drying system based on the moisture content (MC), moisture content ratio (MR) and drying rate (DR) were examined. The experimental results showed that the S-SDC can reduce the moisture content of kaffir lime leaves more rapidly than a conventional solar drying chamber (CSDC). The S-SDC gave a higher DR and decreased drying time compared to that of C-SDC. The results also indicated that operation at higher air velocities resulted in a greater DR, especially at the beginning stage of the drying process. For the S-SDC, the reduced of MC, MR and DR at a high air velocity (v = 2.0 m/s) was better than at low air velocities (v = 0.5 and 1.0 m/s). Drying chamber efficiency is also observed at a higher air velocity of 2 m/s for both SSDC and CSDC. In addition, obtained experimental findings are in line with numerical results. The outcomes of this study present the potential of using the S-SDC compared to the C-SDC to be used in drying crops

Evaluation on the performance of cross-matrix absorber double-pass solar air heater (CMA-DPSAH) with and without thermal energy storage material

The intermittent nature of solar energy source can reduce the performance of solar air heater (SAH) considerably. The utilization of thermal storage materials demonstrates an effective way in order to improve an overall performance of SAH. In the present study, the performance of cross-matrix absorber double-pass solar air heater (CMADPSAH) integrated with the phase change material (PCM) as thermal energy storage was conducted. The PCM material was inserted inside the rectangular aluminium tube used as the thermal absorber. The air mass flow rate of 0.004 kg/s was used during the entire experimental period. The experiment was conducted on several phase; Phase 1 (CMA-DPSAH with PCM) and Phase 2 (CMA-DPSAH without PCM) in order to compare and evaluate the effectiveness of the PCM utilization. Based on the result, CMA-DPSAH with PCM performed better than the CMA-DPSAH without PCM with maximum of heat gain and temperature output were 127 W and 53 oC, respectively. The instantaneous efficiency of CMA-DPSAH with PCM consistently higher than the CMA-DPSAH without PCM for about 17 – 19% with the maximum was 64 % during the low radiation flux. This feature offers a great potential of solar air heater application in the intermittent solar radiation condition, especially for drying of the agriculture products