Thermal Properties of Solar Collector Comprising Oscillating Heat Pipe in a Flat-Plate Structure and Water Heating System in Low-Temperature Conditions

Abstract

Solar collectors are very important to the photothermal utilization of solar energy in low-temperature conditions. In this paper, a solar collector comprising an oscillating heat pipe in a flat-plate structure is designed and studied experimentally. The thermal properties are studied in detail, and we finally obtain the startup temperature and the expression of the instantaneous efficiency with a relative error of 5%. The results show that the impact of inclination angles on the startup properties of the solar collector is significant to the thermal properties. The comparisons of the efficiency of the present design and similar products are also displayed and discussed, showing that an oscillating heat pipe collector in a flat-plate structure overcomes the low efficiency, high startup temperature and bad pressure resistance of conventional solar collectors. In addition, the thermal properties of the water heating system based on the novel collector were also tested, illustrating the differences between the solar irradiance and the water heating system. Some improvements (e.g., shell material and assembly method) were made in this system design process to increase the heat transfer efficiency and solve the corrosion and pressure resistance problems.

Thermal Performance Enhancement in Flat Plate Solar Collector Solar Water Heater: A Review

“…Pandey et al [21] reviewed seven types of FPSC development which include; utilization of polymer material as absorber plate [24], modification of riser tube into a mini and microchannel, application of nanofluids [25,26], modification of absorber plate designs, employment of phase change materials, reduction of heat and usage of enhancement devices. Sakhaei and Valipour [4] discussed four methods, which include applications of turbulators, enhancement devices [27], heat loss reduction [28], phase change material (PCM) and nanofluids [29].…”

Solar Photovoltaic Tracking Systems for Electricity Generation: A Review

“…The latest generation of solar collectors is frost resistant, highly efficient in all weather conditions, with low thermal inertia, with heat pipe operation and with one thick layer of glass around all active collector parts; this means that the temperature of the heating fluid rises very quickly, which allows the collector to utilize the heat even at extremely short sunlight intervals. A similar solar collector is represented by Gao et al [42] with an oscillating heat-pipe collector and flat-plate structure. This type of solar collectors overcome the poor pressure resistance of conventional solar collectors, low efficiency, and high startup temperature.…”

Performance Evaluation of Flat Plate and Vacuum Tube Solar Collectors by Applying a MWCNT/Fe3O4 Binary Nanofluid

“…where, ρ bf is the density of the working fluid, and ϕ is the volume fraction of the working fluid. The density and specific heat of the MWCNT/Fe 3 O 4 binary nanofluid can be calculated using Equations (4) and (5), which are defined by Hemmat et al [34]: Table 4 shows the density and specific heat of the water and the MWCNT/Fe 3 O 4 binary nanofluid. The efficiency of the solar collector can also be calculated from Equation (6):…”

“…The developed simulation models predicted the exit temperature, absorption plate temperature, energy efficiency, and heat loss parameter within the maximum error of 9%, and the thermal efficiency of the manufactured tubular solar collector was 71%. Gao et al [5] presented experimentally that the heat pipe type flat plate solar collector showed a large variation in thermal characteristics depending on the gradient angle, with a maximum efficiency of 74.3%, which was superior to those of other similar designed ones. Even though there were many attempts to increase the effectiveness of the solar collector by the change of structure, the method of structural change in the solar collector has technical limitations.…”