Solar Air Heating Collector Research Articles

Outdoor performance investigation of a thermoelectric cooler-integrated solar air heating collector

Solar air heating systems are continuously being improved by combining them with other energy conversion technologies. In this paper, outdoor tests were carried out on a thermoelectric heat-pumping solar air heater (TE-SAH), with four (04) TECs (TEC1–12706) attached to the backside of the absorber plate, and powered by a 40Wp mono-Si PV module to pump heat from the absorber plate into the heated air. The thermal energy production, energy efficiency, heat loss coefficients, and heat removal factor were evaluated and compared with a reference system without TECs. The heat collection and energy efficiency of the solar air heater were improved by 7.14 % and 66.71 %, respectively, with the integration of TECs. Heat losses also decreased by 0.46 MJ. Furthermore, the estimated heat removal factor for the TE-SAH was 0.55, higher than 0.49 obtained for the reference SAH. These results showed that PV-TE heat-pumping is a viable means of improving the thermal performance of solar air heaters.

Numeric simulation and experimental validation for a Novel Trapezoidal Solar Collector

In a global warming context, the diversification of the energy matrix is essential for mitigation. Technologies and solar devices have begun to play an important role in this sense, being flat-plate solar collectors the most practical device. On the other hand, numerical modeling and experimental validation are important tools for improving the performance of these technologies. In this work, a trapezoidal solar air heating collector for food drying processes was modeled by using the Simusol open-access software, and experimental validation was performed. This particular shape presents a geometrical novelty since no other similar designs were found into the available literature, even in such application as food drying. Key parameters, such as air temperature, global efficiency, air mass flow, global heat loss coefficient, and useful heat, are determined and discussed. The proposed air collector numerically behaves as expected. The output air temperature reaches about 100 °C, while the peak heat gain is about 900 W, which makes the air heating collector suitable for drying applications. Due to natural convection is the main heat transferring mechanism, low air mass flows were obtained. For the case analyzed here, this last parameter ranges in 0.012–0.016 kg/s for the optimal thermal behavior.

Energy saving using solar air heater collectors

In this study, the issue of providing heat energy to a small utility room from a solar air heater collector in the climate of Uzbekistan was considered. A diamond-shaped heat exchange accelerating element is used in the installed solar air heater collector. The total working surface is 1 m2. After installing the solar air heater collector, the thermal energy balance of the service room was compiled. As a result, it was determined that 81355 W of thermal energy is required during the day to maintain the room temperature at a normal level. The amount of heat required for the sunny time of the day was 28873 W. The amount of heat received from the solar air heater collector was 1350 W. As a result of the calculations, it was found that the total working surface is 21 m2 on average to provide 100% of the required amount of heat in sunny weather with the help of a solar air heater collector. The calculation process was carried out for 06.01.2023. Covering the daily amount of heat required by the consumer with the help of a solar air heater collector is considered very complicated and requires a lot of money. Therefore, during the design of the heat supply from the solar air heater collectors, it is appropriate to determine the average amount of heat for the season at 15-20%.

Hydrodynamic processes that occur in a solar air heater collector with a triangle channel

In this article focuses on the hydrodynamic processes that occur in the solar air heater collector with a bottomless triangular channel working at the expense of solar radiation. Factors that directly affect the heat exchange processes in the working Chamber of the solar air collector with an overhead triangular shape have been analyzed, including air flow in the channels, heating surface structures, acceleration of the heat exchange process and methods for calculating the main indicators such as pressure loss. The solar air heater is one of the main and widely used equipment that can convert solar energy into useful thermal energy. Solar air heaters are economically efficient due to their simple structural structure and can be widely used in household and industrial sectors. The main area of application of solar air heater collectors is heating, in addition to agricultural, fruits and vegetables, including various products, the drying of technological products can be widely used.

Determining the optimal placement scheme and height of elements that accelerate heat exchange processes in solar air heater collectors through mathematical modeling

In the article, the heat exchange accelerating elements used in the collectors of solar air heaters were investigated by thermal and hydraulic mathematical modeling by changing the location scheme and geometric dimensions in homogeneous environment. In this case, the height of the gap between the flat absorber and the transparent glass was 60 mm. The height of elements that accelerate heat exchange processes has increased from 10 mm to 60 mm. The location scheme is laid out in a corridor and a checkerboard pattern. According to the modeling results, the results of the solar air heater collector with the rhombic heat exchange accelerating element were found to be high.

Development and experimental research of solar air collector

The article is a research and development of a solar air collector for air heating using a metal absorber in the form of chips. The work describes the design of the collector, the principle of its operation and the results of experiments conducted under natural conditions. Experimental data demonstrates that the use of chips increases collector efficiency by 13% and also provides reliable air heating. Analysis of the results under different solar radiation conditions highlights the robustness of the collector and its applicability in a wide range of climatic conditions. The results obtained allow us to conclude that the use of solar air collectors with a metal chip absorber is promising for the efficient use of solar energy in heating systems.

Optimization of geometrical parameters of the heat receiver of a solar air heating collector

The article presents the optimization of the radiant surface of the solar air heating collector (SAH). As a radiation-receiving surface of the SAH, a surface is used, which is a system of metal drainage shavings and a V-shaped surface. Based on the study of the heat transfer process, an effective scheme of heat removal from the radiation-receiving surface of the SAH is presented. When optimizing the radiation-sensing surface of the SAH, the process of radiation-sensing of the surface, which depends on the geometric shape of the chips, is taken as the target function of the maximum. A formula is proposed for calculating the determination of the transmitted amount of the radiant flux of the sun to the unit of the frontal surface through the shape of the metal shavings from the value of the opening step angle in different thicknesses of the metal shavings. It has been confirmed that the solar radiant flux passing to the unit of the frontal surface through the metal chip shape reaches its maximum value in the following cases: when the chips are 0,002 m thick, they have an optimal angle φ = 58°, the transmitted energy of the radiant flux through the chip shape is E = 31%; with a chip thickness of 0,0005 m, the optimal angle is φ = 42°, the transmitted energy of the radiant flux through the chip shape is E = 41%; with a thickness of 0,001 m, the optimal angle is φ = 50°, the transmitted energy of the radiant flux through the chip shape is.

The influence of artificial turbulization on the efficiency of heat exchange in the channels of solar air heating collectors

The influence of artificial turbulization on the efficiency of heat exchange in the channels of solar air heating collectors

CFD Simulation on the Effect of Adding Dimple Balls Stagger Position on Base Plate on the Performance of V-Corrugated Air Heating Solar Collector

The ever-increasing increase in energy consumption requires great attention. Therefore, efforts need to be made to find new energy sources, such as solar energy. The absorber plate absorbs solar energy in the form of radiation, and heat is transferred by convection to the working fluid through the solar collector. Increasing the thermal efficiency of the solar air collector by modifying the absorption area using a v-corrugated absorber and also increasing the convection heat transfer coefficient by creating turbulence in the heat transfer area. Flow turbulence can be achieved by providing a disturbance in the form of a dimple in the working fluid channel above the base plate. This research was conducted utilizing numerical simulations and experiments. CFD simulation aims to obtain the most optimum ratio of ΔT/ΔP values of diameter and dimple distance using ANSYS Fluent software with a diameter variation of 6mm, 8mm, 10mm, and 45mm spacing; 50mm, and 5mm. Based on the results of CFD simulations that have been carried out on each variation of the distance and diameter of the dimple, it can be concluded that the closer the distance between the dimples, the smaller the resulting pressure drop, and the larger the diameter of the dimple, the greater the resulting temperature value. The use of a larger dimple diameter results in an increase in the heat transfer area and further increases the outlet temperature. The expected ratio is the value of the largest temperature increase and the smallest pressure drop. In the calculation of the total ratio, the dimple diameter of 10 mm with a distance of 45 mm has the highest ΔT/ΔP ratio value.

Manufacturing and Evaluating of Indirect Solar Dryers

–Indirect solar drying uses solar radiation to heat air and dry agricultural products in harvest time to store them for a longer time and reduce waste. The dryer consists of a solar air heater collector, a drying chamber, and an air ventilation system. In this study, an indirect solar dryer system is constructed and ventilated with an electrical fan. Experiments are conducted on the system using eggplant as an agricultural sample on 2 consequent days (29th and 30th October 2022), to evaluate the system data recorded during the drying process in terms of the temperature for points in the system, solar radiation, and the sample mass. The temperature measurements are ambient, collector, and dried chamber outlet temperatures. The results show that the most effective time for solar drying is between 9:00 and 16:00, and the drying system air temperature is raised to about 40°C when solar radiation reached more than 600 W/m2 in the noon time. The weighted mass is used to evaluate the drying process, and maximum drying rate and drying efficiency are obtained on the 1st day of the drying before noon time.

Enhancement of thermal efficiency and development of Nusselt number correlation for the solar air heater collector roughened with artificial ribs for thermal applications.

The thermal efficiency of conventional solar air heater is very low. This research article concentrates on incorporating V-shaped staggered twisted ribs over absorber surface of solar air heater. Various roughness parameters were tested to determine their effect on the Nusselt number, friction factor, thermo-hydraulic performance index, and thermal efficiency. During experiment, the Reynolds number is varied from 3000 to 21,000; while relative roughness length varied for 4.39 to 10.26 and relative staggered distance for 2 to 6. However, relative roughness pitch, twist length, and angle of attack were kept constant. The Nusselt number and friction factor of the roughened collector enhances to 3.41 and 2.56 times that of the smooth collector, respectively. The thermal efficiency of the roughened solar air heater increases to 73.64% of the roughened plate as it was noticed 42.63% for smooth surface due to breakage of the laminar sublayer. The correlations for Nusselt number and friction factor as function of Reynolds number and roughness parameters are also developed. The maximum thermohydraulic performance gained at the optimum parameters of d/e of 4 and S/e of 6.15 is 2.69. The percentage deviation between the developed correlations and the experimental findings shows very satisfactory outcomes. Therefore, it can be concluded that inclusion of twisted V staggered ribs enhances the thermal performance of solar air heater with the lowest frictional penalty.

Improving the energy efficiency of a solar air heater with heat accumulator using flat reflectors

In the article, the authors researched the process of increasing the energy efficiency of the solar air heating collector with heat accumulator. In order to increase the energy efficiency of the solar air heating collector with a heat accumulator, it was proposed to install flat reflectors parallel to its sides. Flat reflectors with a surface area of 1.8 m2 were installed on the sides of the solar air heating collector with a useful surface of 1.8 m2, and a pilot-industrial version of the device was created. According to the results of the conducted research, it was determined that the energy efficiency of flat reflectors depends on the solar declination angle. Research results show that, the maximum heat capacity of the flat reflector solar air heating collector with a heat accumulator was 1020 W. The maximum temperature of the heat carriers, air + 75°C and heat accumulator + 85°C.

Determination of the energy efficiency of a flat reflector solar air heating collector with a heat accumulator

The article presents an improved scheme and pilot-industrial copy of a flat reflector solar air heating collector with a heat accumulator. The heat balance equation of the flat reflector solar air heating collector with heat accumulator is constructed, and its energy efficiency is based on it. Considering the local climatic and meteorological characteristics of the city of Karshi, its useful performance coefficient was determined based on the experiment conducted on the flat reflector solar air heating collector with a heat accumulator. This designed device is proposed as an active solar heating system for the anaerobic digestion of municipal solid waste based on energy and resource efficiency. As a result of experimental studies, a flat reflector solar air heating collector with a heat accumulator’s high energy efficiency was determined in the heating heat carriers (air up to + 75°C and heat accumulators up to +85°C) on February 24, 2023.

The effect of heat losses and heat transfer coefficient on the efficiency of the solar air heater collector

In this Article developed the heat balance equations for a solar air heater with a concave air pipe absorber, calculating the heat wastes lost from the barrier structures of the device. In addition, a special emphasis is placed on the issues of optimal placement of concave air pipes, optimal distances are selected between the air pipes. Issues of increasing its heat giving capacity are solved by the shading placement of concave air pipes. The result is an increase in the performance of the device by increasing the coefficient of heat transfer of the solar air heater collector with a concave air pipe absorber. To do this, the movement of concave tube absorbers with different geometric arrangements was studied. Also in this article, a heat balance equation was developed to determine the optimal geometric location of air pipes and the reliability of the results obtained was confirmed. According to the simulations carried out, the placement of a concave-tube in the form of a checkerboard on the surface of the absorber is calculated, perpendicular to the air flow, parallel to the air flow and in the form of a flat air pipe.

Efficiency enhancement of solar air heater collector by modifying jet impingement with v-corrugated absorber plate

The current work involves an experimental investigation of a modified v-corrugated absorber plate to get a better performance of the Solar Air Heater (SAH) collector. The thermal efficiencies of the modified and the normal v-corrugated collector having a jet plate blown systems are compared to present the actions of the modified system. The modified system is named Model-1, whereas the normal system is called Model-2. The experimentation has been done in winter 2021 in Mosul city, Iraq. The results confirm that the thermal efficiency of Model-1 is more efficient than Model-2 by 11.5 %, 14.5 %, 12.3 % and 13.2 % for 0.009 kg/s, 0.018 kg/s, 0.028 kg/s and 0.037 kg/s, respectively. The optimum thermal performance for Model-1 and Model-2 have been obtained for 0.037 kg/s and equal 82.3 % and 69.1 %, respectively. A substantial temperature difference has been found in Model-1 in comparison with Model-2. The highest outlet temperature of Model-2 is always lower than Model-1 for all mass flowrate. The enhancement in the thermal efficiency of Model-1 indicates that the use of the modified model has a considerable effect on the heat exchange efficiency.

Experimental study on heat storage integrated flat plate solar collector for combined water and air heating in buildings

Combined water and air heating flat plate solar collectors can reduce water and space heating-associated energy costs at minimal installation. This study uses the serpentine copper tubes for water to have a more surface area and flow duration. Baffles are provided to increase air flow residence duration. In addition, multifunctional heat storage tubes are fixed on the absorber. The results reveal that the energetic and energetic performances of the collector are significantly affected by the solar radiation and mass flow rates of water and air. The heat storage integrated collector's peak energy and exergy efficiencies are 88.8 % and 3.5 %, respectively, higher than the collector without heat storage at the water flow rate of 0.025 kg/s and air mass flow rate of 0.0132 kg/s. The overall heat loss coefficient of heat storage integrated collector is 4.2 % lower at a higher flow rate than without heat storage. The heat storage tubes reduce heat loss, increase the absorber area, and compensate for the fluctuation of available solar energy. The presented hybrid solar collector has more economical and environmental benefits than the conventional collector with shorter payback periods.

Experimental study of multi-pass solar air thermal collector system assisted with sensible energy-storing matrix

Analysis of heat transfer around the components of multi-pass solar air heating collector and its performance enhancement has been presented using experimental approach. Radiation and convection heat transfer from the system covers and collector plate to the flowing airstreams in the collector system have been investigated. Geological porous matrix has been used as thermal energy reservoir. Test rig was set up under daily average solar insolation, ambient temperature, wind speed, and relative humidity of 302.40 Wm-2, 29.30 °C, 0.58 ms−1, and 48.53%, respectively. Thermal performance evaluation of the multi-pass solar air collector has been conducted in accordance with the ASHRAE standard specified for the solar air heating systems. Thermal collector efficiency range of 51.91–72.55% has been achieved with an optimum air mass flow rate of 0.013 kgs−1. System evaporative capacity range of 1.158×10−3 - 1.205×10−3 kgs−1 was computed. The matrix has extended the span of system operation for more than 3 h after sunset. Comparison of the outcome of multi-pass solar collector performance with the reported study has been done with good agreement. However, an improvement in performance through heat transfer from collector to the flowing air could be achieved.

Design and thermo-energetic evaluation of a solar building heating system

This paper presents the design, construction and thermo-energetic evaluation of a solar building heating system consisting of a double-pass counter-current solar air heating collector with porous matrix and a water-bed heat storage unit connected to a prototype building located at the National University of Salta, Argentina. The experimental study determined that the solar collector has an average daily efficiency of 37 % while the storage unit has an average daily efficiency of 38 %. The overall daily efficiency of the complete system is 18 %. During the test period, the night-time discharge of the storage unit ensured that the temperature of the room to be heated was always above 20 °C when the outside temperature was between 10 and 15 °C.

Mass flow rate optimization in solar heating systems based on a flat-plate solar collector: A case study

Little works considered the optimization of working fluids in solar systems. Engineers, designers and scientists are interested with the optimization problems, furthermore it is very important specially, for solar systems to improve the energetic behavior and increase their efficiencies as a conversion system of solar irradiance to a useful thermal power. According to the available literature, the criteria of optimization mainly relates to energetic and economic analysis (one of them or both). The analysis was based upon the maximum useful energy obtained from solar collector. Accordingly, the optimum mass flow rate was found aspires to infinity. The second analysis is based upon minimum cost of the unit of useful energy [$/W]. The optimum mass flow rate of solar air-heating flat-plate collector for the considered domestic solar heating system has been found 29 kg/h per square meters of solar collectors. This paper deals with a third criteria that is, the amount of the additional energy required to achieve the required task from the solar system by means of auxiliary heating system. In where both the outlet temperature and mass flow rate play crucial role in the heat exchange between the fluid in the collector loop and the fluid in the load loop.

The Effect of Using the Fire-brick Fragments as a Thermal Energy Storage Material on Thermal Efficiency of Solar Air Heater

The hot air needed in applications such as drying agricultural products and space heating can be obtained with air-heated solar collectors. Air has a lower heat transfer coefficient than water. Using storage materials with increased surface area in air-heated solar collectors provides both obtaining higher temperatures output air and increased the total efficiency of the collector by storing energy. Refractory materials such as fire bricks have low thermal conductivity and high thermal capacities. In this study, the effects of refractory fire-brick fragments which are a kind of refractory in storage and reuse of thermal energy on collector efficiency were investigated. Fire brick fragments of different densities were applied into the solar air heater collector and their thermal efficiencies were compared during under radiation and cooling.