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A performance and technoeconomic study of different geometrical designs of compact single-pass cross-matrix solar air collector with square-tube absorbers
摘要： 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.
关键词： Thermal absorber design,Solar air collector,Cross-matrix absorber
更新于2025-09-23 15:23:52
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Performance improvement of baffle-type solar air collector based on first chamber narrowing
摘要： This paper proposes a novel idea to optimize thermal performance of baffle-type solar air collector by narrowing the first chamber through rearranging the baffles in the collector. The collector with five chambers divided by four baffles was investigated numerically and experimentally, and the mechanism of performance improvement was revealed by flow and heat transfer analysis. The simulation results show that the width of first chamber has significant influence on thermal efficiency, while has little influence on pressure drop. The maximum thermal-efficiency growth rate can be achieved when the width of the first chamber is 200 mm with the total chamber size of 2000 mm × 1000 mm × 120 mm, and the value is up to 16.90% compared with the model with evenly distributed baffles during the Reynolds number ranges from 1.8–5.5 × 10^3. A test rig was developed at the ratio of 1:0.5 to the numerical model. Four collector models were studied under three working conditions, and effectiveness of this method is verified. The results show that the first-chamber narrowing method has relatively stable optimization effect with a thermal-efficiency growth rate ranges from 9.73% to 16.10% in the experiment. It means that this method is not sensitive to scale change and has certain adaptability.
关键词： Experimental verification,Numerical simulation,Performance optimization,First chamber narrowing,Solar air collector
更新于2025-09-23 15:23:52
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Investigative study of the thermal performance of a trial solar air heater
摘要： Solar collectors need to be inclined at the optimum angle to maximize the receiving energy. The evaluation of the thermal performance of solar air collectors is important for the proper design and sizing of the collector for a given application. In our experimental/theoretical study, which consists of a thermal performance investigation, we have sought to optimize the efficiency–temperature rise couple of the designed solar air heater by considering the appropriate assembling materials regarding the absorber, the glazing and the insulation. Obviously, efficiency is dependent on the orientation of solar collectors and the measured parameters climate conditions such as wind speed, solar radiation and ambient temperature. In order to achieve possible performance optimization of the receiver plane using a low number of variables and equations, the calculations were carried out considering four values of azimuth angle, γ = 0°, 22.5°, 45° and 67.5°, and by varying the tilt angle β by 5 degrees from 15° to 70°.
关键词： Insulation,Efficiency,Absorber,Optimization,Experimental solar air collector
更新于2025-09-23 15:23:52
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Solar air collector performance in transient operation under radiative regimes with different levels of stability
摘要： The first objective of this paper is to prove that for the same amount of incident solar irradiation, the amount of useful heat provided by a solar air collector is different during time intervals with stable and unstable radiative regimes, respectively. A simple one-node model is used to analyze the performance of two solar air collectors with similar surface area. One collector has a porous absorber while the other collector has an aluminum U-corrugated absorber. Quantifying the performance of solar collectors during transient operation is more involved than during steady-state operation. Specific instantaneous indicators and variability factors are defined, which show how large is, in average, the relative deviation between the instantaneous and global values of the efficiency and coefficient of performance, respectively. The second objective is to estimate variability factors for different levels of radiative regime stability. Three conclusions are stated. First, when a solar collector performs better on long term than another collector, this is true for all radiative regimes. Second, the instantaneous performance indicators depend on the radiative regime, operation duration and design parameters. Third, the variability factors are smaller (in absolute value) in case of the stable radiative regime than for the unstable radiative regimes. Experimental data confirm that the usual global indicators may be used with reasonable accuracy in case of stable radiative regimes but they should be complemented with variability factors during unstable radiative regimes.
关键词： Transient operation,Solar air collector,Performance indicators
更新于2025-09-23 15:21:21