Performance Of Solar Air Collector Research Articles

Vacuum Effect on the Performance of Solar Air Collector with Micro-Channel Absorber Plate

Vacuum Effect on the Performance of Solar Air Collector with Micro-Channel Absorber Plate

Exergy analysis of single‐flow solar air collectors with different configurations of absorber plates

AbstractIn the current study, an experimental analysis of exergy performance for different absorber plates is done. Three types of absorber plates are supplied with different fin arrangements with a variable air mass flow rate. The exergy analysis to evaluate the exergy performance of the solar air heaters uses experimental data for conventional and finned solar air collectors with different arrangements of fins. The main aim of the current study is to compare the exergy performance of the conventional solar air collector with those equipped with fins. The introducing of the fins in different arrangements enhances the absorber surface area, which leads to increased heat transfer. Also, fins induce air turbulence in the flow field, which improves the exergy performance of solar air collector. It is found that the exergy reduces and exergy efficiency enhances with increasing the airflow rate. The traditional flat absorber plate has undesirable exergy loss and exergy efficiency for all ranges of airflow rates. Thus, the flat plate collector presents the most substantial irreversibility, for which the exergy efficiency is the least. However, the results show that the exergy efficiency of inclined staggered turbulators is higher than that of in‐line and staggered turbulators. The optimal value of exergy efficiency is recorded at nearly 77% for the solar air collectors equipped with inclined staggered turbulators compared with other types of configurations.

Investigative study of the thermal performance of a trial solar air heater

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°.

Experimental Investigation of the Solar Drying and Solar Collector Design for Drying Agricultural Product (Mint)

Drying is basically a phenomenon of removal of liquid by evaporation from a solid. In the following section an attempt is made to provide a concise overview of the fundamental principles of drying process for agricultural product (Mint). Drying basically comprises of two fundamental and simultaneous processes: heat is transferred to evaporate liquid, and mass is transferred as a liquid or vapor within and the solid as a vapor from the surface. The experimental study is investigated in the Biskra city of Algeria for drying mint in the drying room which it integrated with a solar air collector (new design). We have to spread the produce on a suitable surface and let it dry in the drying room and added the study of thermal performance of solar air collector and trying with three different airflow rates, namely, 0.018, 0.028 and 0.034 kg/s are conducted. Finally, the results have been illustrated with mass water content, product temperature, drying room temperature, outlet temperature in both solar collector and drying room and enthalpy of solar collector and drying room.

Parametric study on the performance of solar air heater equipped with louvered fins

A theoretical model is developed in this study to investigate the performance of solar air collector equipped with louvered fins. Parameters, such as mass flow rate, fin spacing, louvered pitch ratio (w/Lp), and louvered angle, are considered. The governing equations are solved using a computer code that employs an iterative solution procedure, and the obtained results are compared with that using plain solar air heater. The thermal efficiency of the plain solar air heater is enhanced from 43.14 % to 76.79 % by employing louvered fins with fin spacing values of 5 and 1 cm at a constant mass flow rate of 0.020 kg/s. However, the pressure drop effect becomes dominant that decreases the effective efficiency by 9.4 % at a high mass flow rate of 0.083 kg/s.

EVALUATE THERMAL PERFORMANCE OF SOLAR AIR COLLECTORS

Solar energy has an important place in sustainable and clean energy sources. Solar collectors can play a vital role among applications of solar energy system. Solar collectors are divided into solar air heating collector (SAHC) and solar water heating collector (SWHC) according to the fluid used. Although its efficiency is low because of air’s worse thermodynamic properties in terms of heat exchange compared to liquid, SAHC is still widely used in the world for the advantages of simple structure, convenient installation and easy maintenance. The absorber surface material is the most important parameter in the design for solar air collectors. The present study aimed to evaluate the thermal performance of solar air collectors. The treatments under this study were three types of solar panels absorbent. Stainless steel, aluminum and iron) and three different air velocities of 1.7, 2.4 and 3.6 m/s represented. Stainless steel solar panels absorbent give the highest value of absorption efficiency, useful heat gain to storage and overall thermal efficiency and they were 86.4, 71.42 and 59.87 %, respectively at midday air flow inlet temperature (Tai =31.7 C°), air flow outlet temperature (Tao =49.9 C°) and Average plate temperature (Tpm =70 C°) at 2.4 m/s fan velocity.

Review on Solar Collector for Agricultural Produce

<span>Among the most important components of solar energy systems, solar collectors are devices that receive solar energy and convert it into thermal energy, as most essential components of solar dryer. This review presents description and previous work performed on performances of solar air collector for agricultural produce. In addition, various solar collectors are classified and described. Solar air collectors for drying application of agricultural produce are presented and summarize. The energy and exergy efficiency of the solar air collector ranges from 28% to 62% and from 30% to 57%, respectively. </span>

Effect of Buoyancy on the Perfomance of Solar Air Collectors with Different Structures

In order to study the effect of buoyancy on the performance of solar air collector, the theoretical analysis and experimental tests of four solar air collectors with different structures under natural convection and mixed convection are carried out. The results show that the air temperature rise of the protrusion-corrugated plate air collector is the highest in the natural convection, which is 9.17 Chigher than that of the flat plate collector, and the air outlet velocity is 0.19 m/s, increasing by 16.88% than that of the flat plate collector. Observing the effects on the heat transfer performance of mixed convection, it can be found, in addition to the protrusion-corrugated plate air collector, the buoyancy plays a positive role on the other three solar air collectors in the upward flow, while the buoyancy plays a negative role on the other three solar air collectors in the downward flow, and the enhanced degree of the buoyancy to the corrugated plate air collector is the largest, while the enhancement degree of the flat plate collector is the least.

Performance analysis of optically semi-transparent material packed-bed solar air heater

This paper deals with theoretical analysis of performance of solar air collector having its duct packed with optically semitransparent materials. The heat transfer equations for two dimensional fully developed fluid flows under quasi-steady state conditions have been developed in order to analyze the thermal, thermo-hydraulic and exergy performance and to study the effect of system and operating parameters. A computer programme is developed in c++ language to estimate the temperature rise of entering air for evaluation of performance by solving the governing equations numerically using relevant correlations for heat transfer coefficient for packed bed systems. Results of air temperature rise and thermal efficiency obtained from the analysis have been compared with available experimental results and results are found fairly in closed agreement. It has been found that there is considerable enhancement in thermal efficiency with packed bed collector. Effect of total bed depth on efficiency show that there is an upper limiting value of total bed depth beyond which the thermal efficiency begins to fall again and this type of characteristics behavior is observed at all mass flow rate. It is also noticed that there exists an optimal value of effective and exergy efficiencies for a given mass flow rate.

The stability of the radiative regime does influence the daily performance of solar air heaters

The dependence of the daily photothermal conversion performance on the stability of the radiative regime has been rarely treated in literature and only for systems based on water collectors. The objective here is to estimate whether the daily performance of solar air collectors is dependent on the radiative regime characteristics other than the level of daily solar irradiation. Results are obtained by comparing the performance of two solar air collectors whose design is almost similar but one has a porous absorber and the other has a U-corrugated absorber. First, the daily performance of the collectors are analyzed experimentally during clear sky days in Bucharest (Romania, South Eastern Europe). The instantaneous performance of the collector based on porous absorber is generally higher than that of the collector based on U-corrugated absorber. Second, dynamic models are developed and validated against measurements obtained in Bucharest. Two new performance indicators specific to time dependent operation are defined. It is shown that these indicators equal each other at steady state but in transitory operation they have different values. Simulations are performed for collectors operation under the climate of Timisoara (Romania). Eight days, covering all four seasons and belonging to different relative sunshine classes and different radiative regime stability levels are selected. At daily level, the collector based on porous absorber is more effective than the collector based on U-corrugated absorber. When the instantaneous performance is considered, the U-corrugated absorber may provide better results in the morning. These findings do not depend on the stability of the radiative regime. The dispersion of the instantaneous performance values is higher for less stable radiative regimes during days with medium cloudiness (daily relative sunshine σday between 0.4 and 0.7) and during days with fully stable radiative regime and overcast sky (σday=0.0). Each collector has a specific behavior when the level of radiative stability and the class of relative sunshine change. During time intervals of transitory operation the traditional coefficient of performance may be used as a substitute of the time averaged value of the instantaneous coefficient of performance. However, the traditional collector efficiency is not a reliable measure of the time averaged value of the instantaneous efficiency.

Intelligent Optimization of Solar Air Heating System in Large Scale Construction of and its Application

The monomer thermal performance of solar air collector is the bottleneck problem of the design application of practical engineering. By combining the experimental and theoretical researches, this paper uses the heating load and thermal efficiency of the optimization module at different flow rates, and puts forward the efficiency normalization treatment method; analyzes the heat transfer intensity, heating capacity, thermal efficiency and indoor heating effect of the module under different operation modes; with the microprocessor as the core, sets up the intelligent control system of solar air heating with multiple sensor information fusion; adjust the running state of fan and heating units according to the changes of indoor and outdoor environment in real time. The practical application shows that the intelligent control system can ensure a comfortable indoor environment and improve the thermal efficiency of the system.

The Theoretical and Experimental Research on Thermal Performance of Solar Air Collector with Finned Absorber

Abstract The theoretical analysis and experimental research on the thermal performance of the solar air collector with finned absorber are made in this paper. The effects of setting angle, medium flow and air inlet mode on solar air collector performance are analyzed, and the theory calculation model of it is confirmed by experimentation. The results show that the error between the theory calculation model and the experiment test maintains at around 9%. The results of calculation and analysis on thermal performance of this collector through theory calculation model indicate that setting angle has no influence on the thermal efficiency, while medium flow has a positive relation with it. In addition, heat-collecting efficiency can be improved by the negative pressure in the collector, but it is dropped along with the pressure going up. In sum, the fin plat solar air collector can be widely applied because it can be the medium-low temperature heat source for the solar drying systems.

Impact of small-world topology on the performance of a feed-forward artificial neural network based on 2 different real-life problems

Since feed-forward artificial neural networks (FFANNs) are the most widely used models to solve real-life problems, many studies have focused on improving their learning performances by changing the network architecture and learning algorithms. On the other hand, recently, small-world network topology has been shown to meet the characteristics of real-life problems. Therefore, in this study, instead of focusing on the performance of the conventional FFANNs, we investigated how real-life problems can be solved by a FFANN with small-world topology. Therefore, we considered 2 real-life problems: estimating the thermal performance of solar air collectors and predicting the modulus of rupture values of oriented strand boards. We used the FFANN with small-world topology to solve both problems and compared the results with those of a conventional FFANN with zero rewiring. In addition, we investigated whether there was statistically significant difference between the regular FFANN and small-world FFANN model. Our results show that there exists an optimal rewiring number within the small-world topology that warrants the best performance for both problems.

Simplified analysis methods for thermal responsive performance of passive solar house in cold area of China

Since the first Chinese passive solar house was built in 1977, a large number of passive solar houses have been built within 20 years. However, many problems appeared during the long-term utilization process, such as poor heating effect, inconvenient operation control and incomplete design standards, which lead to the development of passive solar houses stagnant in the past decade. To solve the above- mentioned problems, technical improvement and free running temperature prediction methods of passive solar house were investigated in this study. As a case study, a two-year experiment was undertaken in an improved passive solar house, located in Dalian city, northeast China, and the performance of solar air collector was investigated in winter mainly. The experimental results showed the indoor–outdoor temperature differences were about 13.4–24.5°C without auxiliary heat exchanger. According to the function of useful heat gain and solar irradiance obtained through regression analyses of experimental data, a simple free running temperature prediction formula of passive solar house for engineering application was obtained, which can be expressed as the linear superposition function of three main factors, including outdoor temperature, internal gains and solar irradiance. Taking the improved solar house as an example, a good agreement between monitored data and predicted data proved the feasibility of the prediction formula. In addition, weighed coefficients of influence factors in prediction formula were determined based on five typical cities in cold areas of China.

Optimization of solar air collector using genetic algorithm and artificial bee colony algorithm

Thermal performance of solar air collector depends on many parameters as inlet air temperature, air velocity, collector slope and properties related to collector. In this study, the effect of the different parameters which affect the performance of the solar air collector are investigated. In order to maximize the thermal performance of a solar air collector genetic algorithm (GA) and artificial bee colony algorithm (ABC) have been used. The results obtained indicate that GA and ABC algorithms can be applied successfully for the optimization of the thermal performance of solar air collector.

Thermal performance of solar air collector with transparent honeycomb made of glass tube

Transparent honeycomb structure with thin-walled glass tube as the honeycomb unit is designed and applied to a flat-plate solar air collector. Experiments are performed for solar collectors with six different honeycomb sizes. The emphasis is to study the effects of diameter and aspect ratio of the honeycomb unit on the transmittance and efficiency of the solar collector. It is shown that for the same diameter but different aspect ratios, there are large temperature differences between the collector’s exits; the smaller the aspect ratio, the larger the exit temperature, with a maximum difference of 10°C; for the same aspect ratio but different diameters, the temperature differences are small; the maximum temperature difference between the collectors with and without honeycombs is 12°C. A theoretical expression for the honeycomb transmittance is derived with a simplified method. The result shows that the honeycomb transmittance is only related with the aspect ratio and the materials’ optical properties but not the actual size of the honeycomb.

Flow Control and Unsteady-State Analysis on Thermal Performance of Solar Air Collectors

Promotion of the use of renewable energy, such as solar heat, for space heating and drying crops and wood is desired to prevent global warming. High-temperature collection of heat by air collectors producing as much as 50°C in winter for space heating and about 80°C in summer for exchanging heat to circulating water for hot water supply would be appropriate applications. In this study, first, a flow control system for constant outlet temperature was installed in a hot air supply system to examine the feasibility of the control system. After experiments, it was found that the control system could function satisfactory. Second, an unsteady-state analysis was made to predict the thermal performance of a flat-plate collector under a given condition of variable flow rate. The analytical model became simple by the assumptions that the heat capacity of the air in the collector and heat conduction in the flow direction through the air and the materials of the collector could be neglected. The maximum differences in outlet temperature and collector efficiency for constant flow rate between the analysis and the experiment were 1.8°C and 6% of the collector efficiency, respectively, except in the beginning of experiments. The biggest difference in the collector efficiency was 30% at 3:00 P.M., which occurred at the end of one of the experiments. The analytical results generally agreed well with the experimental results even when the flow rate and solar radiation changed greatly as time went on. Transient effects are important to predict outlet temperature for variable solar radiation intensity, wind speed, and flow rate.

Prediction of the thermal performance of solar air heaters by Internet-based mathematical simulation

This paper presents an internet-based mathematical simulation for predicting the thermal performance of solar air collectors to collect energy used for drying various products. The solution procedure was performed for a flat plate collector and a V-groove absorber. The thermal performance was determined over a wide range of operating conditions, but in the same configuration for the two types of solar collector. The V-groove absorber was found to be more efficient than the flat plate collector. The optimum operating conditions were determined. Comparison between predicted and experimental results indicates that the proposed mathematical model can be used for estimating the thermal performance of solar air heaters with reasonable accuracy.