Thermal performance of a double-pass solar collector with porous media (original) (raw)
Related papers
Thermal performance of the double-pass solar collector with and without porous media
Renewable Energy, 1999
This paper presents the thermal performance of a double-pass solar collector with and without porous media in the second or lower channel of the collector. The experimental setup has been designed to study the thermal performance over a range of design and operating conditions. Several important relationships between the design and operating conditions have been obtained. These relationships effect the thermal performance of the double-pass solar collector. The relationships include the effect of changes in upper and lower channel depth on the thermal efficiency with and without porous media. Moreover, the effects of mass flow rate, solar radiation, and temperature rises on the thermal efficiency of the double-pass solar collector have been studied. The study concluded that the presence of porous media in the second channel increases the outlet temperature, therefore increases the thermal efficiency of the systems.
Evaluation of thermal efficiency of double-pass solar collector with porous–nonporous media
Renewable Energy, 2009
The double-pass solar collector with porous media in the lower channel provides a higher outlet temperature compared to the conventional single-pass collector. Therefore, the thermal efficiency of the solar collector is higher. A theoretical model has been developed for the double-pass solar collector. An experimental setup has been designed and constructed. The porous media has been arranged in different porosities to increase heat transfer, area density and the total heat transfer rate. Comparisons of the theoretical and the experimental results have been conducted. Such comparisons include the outlet temperatures and thermal efficiencies of the solar collector for various design and operating conditions. The relationships include the effect of changes in upper and lower channel depth on the thermal efficiency with and without porous media. Moreover, the effects of mass flow rate, solar radiation, and temperature rises on the thermal efficiency of the double-pass solar collector have been studied. In addition, heat transfer and pressure drop relationships have been developed for airflow through the porous media. Close agreement has been obtained between the theoretical and experimental results. The study concluded that the presence of porous media in the second channel increases the outlet temperature, therefore increases the thermal efficiency of the systems.
Review of the application of phase change material for heating and domestic hot water systems
Heating and domestic hot water (DHW) systems account for 75% of energy consumption in residential, commercial, and industrial sectors. Furthermore, thermal energy storage strongly reduces energy consumption. Storage devices of thermal energy from phase change material (PCM) are essential in solar thermal and waste heat energy technologies that match energy supply to demand and enhance their thermal performance. The storage of PCM thermal energy is more beneficial than sensible energy storage because of its high density of storage energy per unit volume/mass. This review presents previous works on thermal energy storage as applied to DHW and heating systems. PCM has been used in different parts of heating networks and DHW systems, including solar collectors, storage tanks, packed beds, and duct networks. Researchers have also investigated the application of PCM in heating and DHW systems to reduce greenhouse gas emission and electrical power consumption. Hence, PCM thermal energy storage is expected to lower cost and the volumes of heating and DHW systems.
Experimental Investigation of SAHs Solar Dryers with Zigzag Aluminum Cans
This experimental study investigates the thermal performance of two different solar-air collector designs for Ramadi climate conditions. Two types of absorber plate are fabricated and tested. Type (I) uses an absorber plate without cans, whereas Type (II) uses one with cans, these cans are arranged in a zigzag pattern. These collectors are a single-duct double-pass type. Air first enters through the inlet and then passes over the absorber plate before returning underneath the absorber and moving toward the outlet duct. Moreover, the plate is covered with 4 mm thick glass. An axial fan is used for air circulation. As a result, the increase in temperature difference is approximately 3 °C to 10.5 °C when using aluminum cans with a zigzag array. The increase in thermal efficiency between Types I and II is approximately 20%. Additionally, at an average mass flow rate of 0.075 kg/s, the difference between the practical and theoretical thermal efficiencies for the two models is approximately 3%.
Solar Energy, 2019
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 geo-metries 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.
Review of solar dryers for agricultural and marine products
Renewable & Sustainable Energy Reviews, 2010
Drying for agricultural and marine products are one of the most attractive and cost-effective application of solar energy. Numerous types of solar dryers have been designed and developed in various parts of the world, yielding varying degrees of technical performance. Basically, there are four types of solar dryers; (1) direct solar dryers, (2) indirect solar dryers, (3) mixed-mode dryers and (4) hybrid solar dryers. This paper is a review of these types of solar dryers with aspect to the product being dried, technical and economical aspects. The technical directions in the development of solar-assisted drying systems for agricultural produce are compact collector design, high efficiency, integrated storage, and long-life drying system. Air-based solar collectors are not the only available systems. Water-based collectors can also be used whereby water to air heat exchanger can be used. The hot air for drying of agricultural produce can be forced to flow in the water to air heat exchanger. The hot water tank acts as heat storage of the solar drying system.