Solar Heat Collector Research Articles

Energy, exergy, economic and environmental assessment of the triangular solar collector assisted heat pump

The solar air collector assisted air source heat pump is demonstrated to be an efficient clean heating technology, while the research on its working modes, and the corresponding energy, exergy, economic, environmental (4E) analysis is insufficient. In this study, a novel triangular solar air collector assisted air source heat pump (TSAHP) for building heating is proposed, and three working modes including preheating, series and parallel modes are illustrated. The energy model is established and used to determine the optimal working mode, and solved by Python environment. Four scenarios including TSAHP with three areas of triangular solar air collector (TSAC) and conventional air source heat pump (ASHP) are compared based on the optimal working mode. Thermodynamic performance of the four scenarios under different working conditions is analyzed, and result indicate that the TSAHP with 3 m2 TSAC can reduce the power consumption and exergy destruction of ASHP components by 321.9 kWh and 784.6 MJ respectively during the whole heating period. Economic evaluation shows that TSAHP has the shortest payback period with moderate TSAC area, and has economic advantages at low nominal interest rate and high electric power cost with large TSAC area. In addition, based on the whole life cycle, 1 m2 of TSAC can reduce CO2 emission by more than 4500 kg.

Energy, economic and environmental analysis of solar-assisted air source heat pump system: a case study in university town

Abstract The integration of solar collector and air source heat pump is solar-assisted air source heat pump system (SA-ASHP), which is regarded as a promising technology in carbon emission reduction and energy saving. In this paper, a SA-ASHP system is designed to supply bathing water for the university town in Shanghai, which can alternately operate with solar-assisted (SA) mode and air-source (AS) mode. The energy performance of SA-ASHP system is simulated with mathematic model, on this basis, its financial benefits and environmental impact have been evaluated and compared with gas boiler water heater. The results indicate that the performance in AS mode and SA mode are affected by the environmental conditions, and the impact on AS mode is more significant. To achieve the optimal performance, the SA-ASHP system operates in AS mode from April to October and operates in SA mode from November to March. As the price of natural gas is higher than electricity and heat pump has good energy-saving effect, the operation cost of gas boiler water heater is much higher than that of SA-ASHP system. After the start of carbon trading, the operation of gas boiler will bring great amount of pollutant emission cost, and SA-ASHP can bring the environmental benefit of ¥ 1 165 654.

Computer technology applications to calculate the insolation of photoelectric power plant

The article considers the method of calculating solar insolation, the algorithm and the program operation for calculating insolation, the graphs are obtained showing the change in solar radiation due to the influence of weather factors and the location of solar-heat collectors installation. The results of the study of the regionally adapted photoelectric power plant using the developed computer model in the Simulink program are presented. The developed model allows to investigate the influence of the main input parameters, such as: latitude and longitude of the power plant installation, difference between the local official time and Greenwich Mean Time, inclination angle of the solar panel, the simulated day, atmospheric transparency factor, albedo and azimuth angle on the insolation intensity of the photoelectric power plant. The obtained dependences can be taken into account in the optimization of power supply systems that use solar energy conversion.

A hybrid TEG/evacuated tube solar collectors for electric power generation and space heating

The present work aimed to examine the performance of a thermoelectric generator (TEG) augmented with a hydronic evacuated tube solar collector heat exchanger used to heat a cold zone. TEGs were operated on the temperature difference between hot water circulated through the heat exchanger and the cold temperature of the surrounding space. The setup model of a heat exchanger with TEGs installed on the outer surface was examined numerically under steady state conditions for natural and forced convection modes. The results obtained show that 1.03 W of electricity could be produced when the temperature differences across the TEG and air velocity are 60 °C and 0.5 m/s, respectively. Also, an increase of 17.47% of TEG power was achieved for each 5 °C drop in surrounding space temperature and by 11% for each 5 °C rise in circulated hot water temperature. Besides the importance of improving TEG efficiencies, the amount of generated electricity may be valuable when large-surface area heat exchanger units are installed in large systems.

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.

Economic feasibility of heating source conversion of the swimming pools

Conversion from conventional heating systems is developed to address the emission of CO2 in the environment, global warming, rising costs, potential shortages of fossil fuels, for all energy source alternatives available. This study reviewed the economic feasibility associated with converting the current heat source to a renewable energy source of heating swimming pools located in Jordan. Many modern heating systems techniques are proposed in this study such as solar heat collectors, heat pump and photovoltaic assisted heat pump. Solar heat collectors are a device that collects and/or concentrate solar radiation from the sun and allow for heating the water. In addition, a growing interest in photovoltaic/heat pump systems is considered, which combines photovoltaic cells and heat pump systems. Hence converting solar energy into electricity and then heat through the heat pump. The Initial and operation cost for all proposed techniques is evaluated. As a result, it is found that the best economical alternative option that can be installed on the available area of the building is photovoltaic with a heat pump system during the heating season. The operation cost of the current source (diesel boiler) is about 179,974 US$ and the total cost of heat solar thermal collector is about 936,540 US$ but the total cost of the proposed photovoltaic/heat pump system is nearly 251,060 US$, which save about 45,134 US$ yearly of the total commercial building electricity bill that is selected with a payback period of fewer than two years. In addition, available space on the rooftop of the selected building is well fitted with photovoltaic panels which are around 2000 m2. This result suggests that utilizing a PV/HP system for hotel pools is advantageous both financially and environmentally.

Performance analysis of a solar heat collector through experimental and CFD investigation

In order to attain maximum efficiency in a solar drying system, continuous effort is made to the key component of solar dryer – solar heat collector (SHC). This research aimed to evaluate the thermal performance of SHC with different flow configuration in the air passage, namely single-pass (S-SHC) and multiple-pass (M-SHC), under natural convection (average air velocity = 0.2 m/s). In order to study the flow and heat transfer characteristics across the SHC, performance analysis was carried out by Computational Fluid Dynamic (CFD) simulation and later validated by experimental results. From the simulation model, the collector outlet temperature and efficiency of M-SHC at maximum solar radiation were 67.4 °C and 10.04%, respectively with percentage error of 8.6% and 17.79% to the experimental results. The presence of recirculation region indicated extended drying air residence time in the M-SHC, resulting in high temperature growth from 8.8% to 12.1% across the air passage compared to S-SHC. In addition, heat transfer enhancement in M-SHC was achieved by compensating radiation heat loss observed in S-SHC through the modification of airflow configuration. Both experimental and theoretical analysis in this study showed that the proposed enhancement significantly improved the performance of SHC having air passage made from recycled aluminium cans.

ОСОБЛИВОСТІ ВИКОРИСТАННЯ АЛЬТЕРНАТИВНИХ ДЖЕРЕЛ ЕНЕРГІЇ В ГОТЕЛЬНИХ ЗАКЛАДАХ

The purpose of the research is to find out the specifics and feasibility of using the alternative energy sources in hotel enterprises of Ukraine. The rate of development of renewable energy sources in our country over the past 7 years has been analyzed, the main directions of alternative energy have been highlighted. The total installed capacity of renewable energy facilities in Ukraine as of the end of 2021 reached 9,225 MW. At the moment, the capacity of all solar power plants is 6351 MW (SPP), wind power plants is 1593 MW (WPP), the energy of solar power plants of private houses is 933 MW, the energy of biomass power plants is 119 MW, the energy of biogas power plants is 111 MW, the energy of small hydropower plants is 118 MW. The analysis of the state of use of alternative energy sources in hotel complexes was carried out in order to reduce the costs of utility services. The possibilities of reducing the energy dependence of hotel complexes and ecology of modern hotels are considered. The problems and prospects of using renewable energy at hotel enterprises are characterized. The most common systems of alternative sources have been considered, such as solar collectors for heating or heating hot water, wind generators and solar power plants for conversion into electrical energy, biogas plants for heating systems, and heat pumps of four types for heating and air conditioning systems. Examples of their application in existing hotel enterprises of Ukraine are given, the approximate cost and sequence of actions for obtaining permit documentation before the start of installation are estimated. The concept of "alternative energy sources" has been defined. The analysis of the features of the use of alternative energy sources in hotel complexes of Ukraine has been done. The renewable energy projects have been characterized. The assessment of the problems of formation and prospects for the use of renewable energy in hotel enterprises is given. The economic effect from the commissioning of alternative energy supply systems has been calculated, the positive and negative aspects of their use are assessed. The positive ones include saving energy resources, partial or full energy autonomy, a positive impact on the branding of the hotel enterprise due to the use of green energy. It gives a potential opportunity to expand the number of consumers of the hotel product. The disadvantages are high cost of equipment, difficulties with permit documentation and some individual features of system installation.

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.

Modeling of a solar air collector heat transfer coefficient with regression algorithms

Modeling of a solar air collector heat transfer coefficient with regression algorithms

Thermal Performance of Greenhouse Heating with Loop Heat Pipe Solar Collector and Ground Source Heat Pump

Thermal Performance of Greenhouse Heating with Loop Heat Pipe Solar Collector and Ground Source Heat Pump

Effect of 450 protruded and dimpled rib height on the performance of triangular duct solar heat collector

With the aid of the solar heater collectors, the thermal energy is collected and transformed into heat. The friction and heat transfer features are significantly influenced by the collector's cross-sectional shape. Using a computational technique, the performance of a triangle duct solar heat collector (TDSHC) roughened with 450 protrude and dimpled ribs was investigated in this study. The performance measurements were extended using computational fluid dynamics techniques. The fluid domain has been divided into finite volumes and Re-Normalized group with enhanced wall treatment has been used for model the turbulence. The performance of TDSHC has been measured by varying Reynolds number from 4000 to 20000 and ratio of protruded to dimpled height to print diameter from (ePD/Pd) 0.5 to 1.25 while ratio of protruded to dimpled obstacle pitch (PPD/ePD), ratio of protruded dimpled height to hydraulic diameter (epD/Dh) and Flow attack angle (αPD) of protruded dimpled obstacle have been kept constant at 7.5, 0.032 and 450, respectively. The results of numerical studies have been recorded in the form of Nusselt number (NuPD), friction factor (fPD) and Thermo-hydraulic performance (η). In contrast to various geometric parameter values, it has been discovered (ePD/Pd) = 1 produces the greatest.(η).

Characterization and thermophysical properties of erythritol/expanded graphite as phase change material for thermal energy storage

The main aim of this paper is to enhance the thermal conductivity of erythritol as phase change material (PCM). The expanded graphite (EG, thermal conductivity: 151 W/(m•K)) is dispersed into erythritol (melting point: 118 °C, thermal conductivity: 0.844 W/(m•K)) as the high thermal conductivity additive, in which erythritol can be adsorbed effectively. The 2% EG/erythritol composite PCM has better cycle stability and its thermal conductivity enhances obviously. The 1% calcium pimelate (CaPi) is used as nucleating agent to inhibit the supercooling of the composite PCM further. The 2%EG/1%CaPi/erythritol composite PCM starts to solidify at 98.5 °C and the equilibrium temperature is about 115 °C during 100 cycles. The latent heat is 352.66 J/g and the thermal conductivity measured by the laser flash method is 1.287 W/(m•K), which is 52.5% higher than pure erythritol. Therefore, it is a new candidate to be used in waste heat recovery, solar energy medium temperature heat collection and other fields.

Performance of a new active solar heat storage–release system for Chinese assembled solar greenhouses used in high latitudes and cold regions

Various active solar heating systems have been developed to enhance the Chinese assembled solar greenhouse winter cultivation capacity by using renewable energy rather than traditional fossil fuel resources. These systems involve an efficient heat-collecting and transfer pattern, which solar energy can be converted into heat energy and flexibly utilized according to heating requirements, without unwarranted heating. To improve CASG thermal performance in high latitudes and cold regions, we modified the water-circulating solar heat collection and release system. The new structure was able to collect the solar radiation on the sheet during daytime to further generate heat through the magnetron sputtering plate. The collector also functions as a heating radiator during nighttime to protect crops from chilling injury in frigid weather. Field tests and economical analysis were performed to investigate the system’s thermal and energy-saving performance by analyzing several core parameters. Test results indicated that the average daily heat collection ratio of the system was 70.2%. The minimum nighttime indoor air temperature heated by the system was increased by 3.5 °C on average and maintained the temperatures above 9 °C after 2–3 cloudy days. The mean COP in heat collection and release phase were 8.2 and 2.4 over a period of 7 test days, respectively. The energy saving efficiency of the system was 44.1%. The novel system proposed in this study using thermal insulation structure and reasonable mass area ratio enables higher heat storage capacity and structure practicability. We demonstrated that the novel technology proposed in this study displayed energy saving characteristics. The new active solar heating system can be effectively used in high latitudes Chinese assembled solar greenhouse winter cultivation.

Improving the Performance of Solar Heat Collector Using Molten Salts

An individual solar collector and two partly freight cylinders filled with molten salts embedded storage tank were connected to each other and forced circulated water by electric pump to improve the thermal performance of residential solar hot water tank. Multi flow rates of 25, 50 and 70 l/h. used to achieve an appropriate flow rate of circulating water. The calcium nitrate tetra hydrate Ca(NO3)2-4H2O and magnesium nitrate hex hydrate Mg(NO3)2-6H2O were mixed to form cheap binary molten salts base on different weight ratios. These molten salts combined could be used as both sensible heat materials and latent heat storage materials, besides they can directly use as heat transfer fluid due to freezing temperature. Six samples of different mixing ratio of molten salts had tested to assess the thermal analysis of each sample. The result indicated that the mixture 60%Ca(NO3)2+40%Mg(NO3)2 had the best performance for thermal storage tank with melting point of 38°C and the thermal value is 8.7 mW, and thermal stability of molten salts were noticed by DSC 60 SHIMADZSU devise.

Comparison between double slope solar still and fourfold slope solar still: energy, exergy, exergoeconomic, and enviroeconomic evaluation

Abstract This paper proposes a single basin fourfold slope solar still, which includes a fourfold slope glass cover plate used for solar heat collection and steam condensation. In order to show the efficiency of the fourfold slope solar still, comparative experiments are conducted under the winter climate conditions in Hangzhou for testing the operational performance of a double slope type solar still (DOSS) and the fourfold slope still (FOSS), so as to make a comparative analysis between them. Results show that the productivity of the fourfold slope still is 19.51% higher than that of the double slope still, and the fourfold slope solar still enhances the average hourly energy efficiency by 31.11%. According to the energy method, the energy payback time values of the fourfold slope solar still and double slope solar still are 64.88 months and 75.42 months respectively. According to the environmental parameter method, FOSS and DOSS reduce 5.47 tons and 4.58 tons of CO2 respectively. The corresponding values based on the exergy environment parameters are 0.21 and 0.18 tons of CO2, respectively. The fourfold slope solar still has a more obvious emission reduction function than the double slope solar still. The cost of the distilled water of the fourfold slope solar still is 0.28 RMB/kg, and the cost of the double slope solar still is 0.30 RMB/kg. In addition, the environmental and economic parameters of the fourfold slope still and double slope still are 79.29$ (561.37RMB) and 66.35$ (469.76RMB), respectively. While, the corresponding values based on the exergoenvironmental parameter are 3.05$ (21.59RMB) and 2.56$ (18.12RMB), respectively. From the analysis of exergoeconomic and exergoenvironmental parameters, the fourfold slope single basin solar still appears to be more effective.

The energetic, exergetic, and mechanical comparison of two structurally optimized non-concentrating solar collectors for intermediate temperature applications

The highly efficient non-concentrating solar collector is a key component for increasing solar energy penetration at the district level, thereby achieving the “carbon neutrality” goal. The non-concentrating vacuum-type solar collector used for intermediate temperature (100–200 °C) applications is a promising technology that has not been sufficiently explored. In this paper, two structurally optimized non-concentrating solar collectors have been meticulously analyzed from the perspective of structure, energy, exergy, surface stress, etc. Firstly, an outdoor experiment is executed to exhibit their thermodynamic behavior. Thermal resistance networks before and after their structural optimization are formed and the results indicate the thermal resistance that impedes solar collector heat loss has been enhanced by 3.83 and 4.17-fold, respectively. Next, energy and exergy flow charts are established to explain the thermal performance difference and the solar energy conversion in their respective internal components. Finally, the potential room for performance enhancement is further studied via the advanced exergy analysis method which reveals that the exergy destruction can be reduced by 17.74% and 13.90%, respectively. The results are essential for the further development of non-concentrating solar collectors in intermediate temperature applications, and it is also instrumental to realizing the decarbonization in district energy supplements.

An active solar water wall for passive solar greenhouse heating

A high thermal capacity north wall is essential for nighttime heating of Chinese solar greenhouses. However, thermal storage ability of the north wall using regular building materials is limited because of their slow heat conduction restricting heat transfer from wall surface to the depth. This study added an active solar water wall constructed of hollow polycarbonate sheets to the north wall, supplemented by an underground water storage tank, to increase nighttime temperature. To evaluate water wall's thermal effect, a field test was conducted, as well as a theoretical verification. Its performance was evaluated in terms of solar heat collection and release capability, nighttime temperature increase and thermal performance in adverse weather. During the 22 coldest days of winter in Beijing, daily averages of collected heat and heat release rate on the basis of floor area were 0.83 MJ m−2 and 22.6 W m−2, respectively. Average heat-collecting efficiency reached 85.8%, and 80.4% of the collected heat was released for greenhouse heating. Compared to the scenario without the water wall, minimum nighttime air temperature increased by 3.3 °C on average. In particular, nighttime temperature maintained above 6.9 °C that was 4.1 °C higher than that in the control greenhouse during three consecutive overcast days. Retrofitting the water wall into Chinese solar greenhouses can make warm-season crop production feasible throughout winter by eliminating supplemental heating. Besides, the water wall-based system can be a self-contained solar heating system, also suitable for traditional greenhouses. Thermal analysis and economic evaluation show considerable practical application prospects.

Exergetic efficiency analysis of impingement jets integrated with internal conical ring roughened solar heat collector

ABSTRACT In the present work, the exergetic efficiency of a solar heat collector with air jet impingement on an internal conical ring-roughened absorber plate has been analytically determined. The motivation behind the present investigation is to determine the performance of the selected heat transfer enhancement technique in order to bring out the feasibility of the investigation. The geometric parameters of the absorber plate and the jet plate that have been examined are derived from the internal conical ring height , inlet flow diameter , internal print diameter of ring , streamwise pitch , and spanwise pitch . The optimum values of the roughness parameters have been determined. The optimal values of geometric parameters that fetch the highest for in the analyzed range between 4000 and 12,900 are a relative roughness height of , a ratio of internal flow diameter to internal print diameter of ring of , a ratio of ring diameter to ring height of , a relative streamwise pitch of , and a relative spanwise pitch of . As compared with smooth duct, the value of the solar heat collector investigated was found to be enhanced 2.2 times higher under similar analytical conditions.

DETERMINATION OF FLOW SPEED THROUGH THE SOLAR HEAT COLLECTOR

This article shows how to determine the speed at which current flows through a solar heat collector. The results were studied with the help of modern laboratory equipment and the results were analyzed graphically. It also covers the origins of solar heat collectors, their current importance, types of solar collectors, and solar water heating systems. KEY WORDS: solar collector, solar heating system, electricity, lighting module, pump module, Power module, real efficiency, flow rate.