Integrated cross-matrix absorber-phase change material in double-pass solar air heater /
Ahmad Fadzil Sharol
- xxi, 205 pages : Illustration ; 30 cm. + 1 CD-ROM
Faculty of Mechanical and Automotive Engineering Technology
Thesis (Doctor of Philosophy) -- Universiti Malaysia Pahang – 2021
Includes bibliographical reference
The intermittent nature of solar radiation required a solar heater design that can effectively harness the radiant energy and convert it into useful heat. This is especially true when one needs to consider the application of solar energy source related devices in the tropical climatic condition of Malaysia. Therefore, this study aims to design, fabricate and investigate the performance of solar air heater of cross-matrix absorber (CMA) with latent heat energy storage material in the form of phase change material (PCM) integration. The performances of four different types of solar air heaters were investigated. The first test has been done on the influence of staging and zigzag arrangement of square aluminium tube absorber from the single-pass solar air heater with cross-matrix absorber (SPSAH-CMA) configuration. In addition, the heat transfer performance of the solar air heater with the best tube arrangement was evaluated based on the double-pass solar air heater with cross-matrix (DPSAH-CMA) configuration. The comparison studies were conducted between all solar air heaters at an identical operating condition, with the reference made with the conventional flat plate DPSAH. The mathematical modelling of the physical system has been developed, and technoeconomic evaluation has been performed on the DPSAH-CMA configurations. Based on the indoor experimental work, at a mass flow rate of 0.005 kg/s, besides having a large cumulative heat gained rate of 6.12 kW at 900 W/m2, DPSAH-CMA-with PCM was superior as compared to the other solar air heater designs in terms of thermal buffer capability and thermal storage efficiency. The thermal buffer and storage efficiency of DPSAH-CMA-with PCM were -0.81 °C/min and 60%, respectively. Evaluation of convection heat transfer coefficient also revealed that a higher value of 88.87 W/m2 K at a low temperature difference of 7.13°C for DPSAH-CMA-with PCM contributed to better heat transfer and storage performances. In terms of analysis of top losses, the lower average of top loss value of 10.00 W/m2 K by DPSAH-CMA-with PCM led to the higher thermal efficiency value of 68.80%. This value was 5.01%, 15.48% and 17.88% higher than DPSAH-CMA-without PCM, SPSAH-CMA-staging and SPSAH-CMA-zigzag tube configuration, respectively. Evaluation under outdoor conditions revealed that the DPSAH-CMA-with PCM provides a better thermal buffer for stabilizing the output temperature profile at a mass flow rate of 0.004 kg/s. DPSAHCMA-with PCM achieved a better thermal buffer of -0.52 °C/min than other SAHs at the solar irradiance level of 660 W/m2. The maximum achievable value of thermal efficiency for DPSAH-CMA-with PCM and -without PCM was calculated to be 44.97% and 27.00%, at a solar irradiance of 400 W/m2 and 320 W/m2, respectively. The mathematical model is developed based on the K-value method derived from the Nils’ correlation for DPSAH-CMA configuration. The cost-benefit ratio for DPSAH-CMA-with PCM was determined to be 0.17 RM/kWh. In conclusion, the application of DPSAH-CMA-with PCM proved beneficial to the application of solar-related drying processes, especially in the tropical climatic condition country such as Malaysia.
THE0009408 (Local)
Faculty of Mechanical and Automotive Engineering Technology