- 标题
- 摘要
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- 实验方案
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Performance Evaluation of Short Parabolic Trough Collectors Integrated with a Small-Scale Solar Power and Heating System
摘要： An investigation is presented on the performance of a small-scale solar power and heating system with short parabolic trough collectors (PTCs). The steady-state model of the short PTCs is evaluated with outside experiments. The model mainly contains the heat loss of the receiver, the peak optical efficiency and the incident angle factor consisting of incident angle modifier and end loss. It is found that the end loss effect is essential in this model when the length of the PTCs is less than 48 m, especially in the winter. The standard deviation of the steady-state model is 1.4%. Moreover, the potential energy efficiency ratio of the solar power and heating system is considerably larger than the coefficient of performance (COP) of general air-source heat pumps, and increases with the decrease of the condensation temperature. An overall system efficiency of 49% can be reached. Lastly, the existence of a water storage tank improves the flexibility of heating the building, and the volume of the water storage tank decreases with the increase of the heating water temperature.
关键词： practical operating characteristics,parabolic trough solar collector,thermal performance,testing method,small-scale
更新于2025-09-23 15:23:52
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Thermal performance analysis of a novel linear cavity receiver for parabolic trough solar collectors
摘要： The trough solar thermal power generation system is one of the most mature solar thermal power generation systems. A novel major arc-shaped linear cavity receiver with a lunate channel based on the black cavity effect principle for parabolic trough solar collectors is proposed in this work. The effects of the inclination angle, collecting temperature, surface emissivity and aperture width on the heat loss are thoroughly analyzed with a two-dimensional numerical model coupling natural convection with surface radiation. In addition, the thermal performance of the proposed linear cavity receiver is compared with that of the Solel’s UVAC series evacuated collector tube. The results show that: (1) The natural convection heat loss is significantly affected by the inclination angle, while the radiation heat loss is mainly affected by the surface emissivity and the collecting temperature. (2) The aperture width of the receiver has a great impact on the thermal performance. The larger the aperture width is, the greater the heat losses. However, the aperture width can also affect the optical performance and the manufacturing cost. The reasonable aperture width for this kind of linear cavity receiver is about 50–70 mm with consideration of all these factors. (3) The proposed linear cavity receiver demonstrates comparative or even better thermal performance as traditional evacuated collector tubes, especially in high temperature range. In general, the proposed linear cavity receiver has the comparative shape and size as the traditional evacuated collector tubes. More importantly, it has the advantages of raising the collecting temperature and reducing the production and maintenance costs. Therefore, it can be used to replace the evacuated collector tube which has poor performance due to long-term operation.
关键词： Cavity receiver,Parabolic trough solar collector,Surface radiation,Natural convection,Thermal performance,Linear receiver
更新于2025-09-23 15:23:52
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Passive cooling of building-integrated photovolatics in desert conditions: Experiment and modeling
摘要： The ef?ciency of photovoltaic modules depends mainly on the cell operating temperatures. Performance enhancement of building-integrated photovoltaic (BIPV) panels by passive cooling has been investigated both experimentally and with computational modeling. It has been shown that mounting the BIPV with a narrow channel can reduce the operating temperature of the photovoltaic panel. This enhancement in the heat transfer from the PV panel results in decreasing the average temperature of the PV panel from 5 to 10 (cid:1)C. Results show that having a 30 cm channel beneath the panel can increase the electrical output by 3e4%. This increase in PV output can translate into a signi?cant amount over the life cycle of a given PV module. Various channel aspect ratios have been tested in order to correlate the enhancement in performance to the cooling channel geometry. There is signi?cant consistency between the experimentally measured PV panel surface temperatures and those obtained from the computational model.
关键词： Building-integrated,Thermal performance,Passive cooling,Photovoltaic array
更新于2025-09-23 15:23:52
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Experimental evaluation of volumetric solar absorbers – Ceramic foam vs. an innovative rotary disc absorber concept
摘要： This paper presents the experimental evaluation of two volumetric solar absorber concepts. It compares the thermal performance of conventional foam absorbers with that of an innovative rotary disc absorber design. The moving absorber showed advantages regarding air temperature stability at the outlet and better operability compared to the foam absorber. Unfortunately, it is shown that the innovative rotary disc design in its present form is not competitive, neither in terms of thermal performance, nor regarding mechanical reliability and robustness. The future task is therefore to optimize the mechanical design regarding thermal fatigue, in order to obtain a robust and durable rotary absorber that can be thoroughly evaluated experimentally.
关键词： volumetric solar absorbers,ceramic foam,thermal performance,rotary disc absorber,mechanical reliability
更新于2025-09-23 15:21:21
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Parametric analysis on the combustion and thermal performance of a swirl micro-combustor for micro thermophotovoltaic system
摘要： A swirl micro-combustor which has strong capability to stabilize the flame has been developed and is promising to be used in micro thermophotovoltaic power generators in this work. Heat recirculation plays a requisite role in flame stability and thermal performance of micro combustors. Thus, the effects of three parameters (center inlet radius w1, swirler width w2, and step height w3) that determine the size and location of the recirculation zones in a premixed hydrogen/air flame are investigated numerically. The results show that inner recirculation zone and corner recirculation zone generated by a swirler are critical for stabilizing the flame. The parameter w1 has an insignificant influence on the thermal performance. Enlarging the inner recirculation zone by decreasing w2 provokes enhanced heat transfer, and increases the temperature level and temperature non-uniformity of combustor walls. The size of corner recirculation zone is increased by increasing w3, which raises the outer wall temperature uniformity. Based on the parametric analysis, the newly designed micro combustor possesses a high wall temperature level. Additionally, the energy output increment is between 9.1% and 14.2% at hydrogen mass flow rate of 0.0006 g/s when stoichiometric hydrogen/air ratio ranges from 0.6 to 1.4.
关键词： Thermal performance,Swirl micro-combustor,Micro thermophotovoltaic system,Recirculation zone,Micro combustion
更新于2025-09-23 15:19:57
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Thermal and electrical performance evaluation of PV/T collectors in Southern India
摘要： Combination of Photovoltaic and solar thermal collectors is used for the simultaneous production of electricity and heat. The proposed research work evaluates the thermal performance of Photovoltaic/Thermal (PV/T) hybrid collectors for the hot and humid weather condition of North Tamilnadu, South India. It is done by providing the cooling arrangement under the collector using wooden duct with baffles. Various parameters influencing the performance of the collector such as solar irradiance, ambient, glazing and tedlar temperatures, air inlet and outlet temperatures at the duct, velocity and mass flow rate of air inside the duct are analysed. The thermal and electrical performances of the PV/T collectors are evaluated under natural and forced circulation of air through the thermal collector. The experimental results are presented in this paper.
关键词： thermal performance,cooling arrangement and wooden duct with baffles,PV/T collectors,electrical performance
更新于2025-09-19 17:15:36
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Performance evaluation on solar box cooker with reflector tracking at optimal angle under Bahir Dar climate
摘要： This paper experimentally investigated the thermal performance of the developed solar box cooker with different reflector configurations. All tests were carried out under Bahir Dar (Ethiopia) prevailing weather condition. Two standard tests, namely stagnation test and sensible heat test were adopted in order to evaluate the thermal performance of the cooker. The highest maximum plate temperature of 148.7 °C can be achieved by the cooker with tracking reflector at optimal angle. In order to evaluate the performance of the cooker, the following performance indexes were employed, thermal efficiency, cooking power and two figures of merit, namely the ratio of optical efficiency to heat loss factor (F1) and the product of heat exchange efficiency factor and optical efficiency (F2). According to the experimental data, the highest computed value F1 of 0.154°C m2/W, can be obtained from the cooker with tracking reflector at optimal angle. The thermal efficiencies achieved by Cooker I, II and III are 37.24%, 32.27% and 33.89%, respectively. Thermal efficiency of the cooker was improved by 9.6% by tracking reflector at optimal angle instead of with fixed reflector. Furthermore, the thermal efficiency was also improved by 15.4% by using aluminum cooking vessel in place of using stainless steel vessel. It can be concluded from the experiments that effective utilization of all solar radiation intercepted on the reflector, and the use of cooking vessel having a reasonably good thermal diffusivity contribute significant roles to improve the cooking performance of the cooker.
关键词： Fixed angle,Solar box cooker,Figures of merit,Optimal tracking angle,Thermal performance
更新于2025-09-19 17:15:36
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Solar Engineering of Thermal Processes, Photovoltaics and Wind || Design of Active Systems
摘要： The liquid and air system configurations described in Section 13.2 are common configurations, and there is considerable information and experience on which to base designs. For residential-scale applications, where the cost of the project does not warrant the expense of a simulation, performance predictions can be done with “short-cut” methods. Design procedures are available for many of these systems that are easy to use and provide adequate estimates of long-term thermal performance. In this chapter we briefly note some of these methods. The f -chart method, applicable to heating of buildings where the minimum temperature for energy delivery is approximately 20°C, is outlined in detail. Methods for designing systems delivering energy at other minimum temperatures, as encountered in solar absorption air conditioning or industrial process heat applications, are presented in Chapter 21.
关键词： residential-scale applications,f-chart method,design procedures,solar heating systems,thermal performance
更新于2025-09-19 17:13:59
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Solar Engineering of Thermal Processes, Photovoltaics and Wind || System Thermal Calculations
摘要： In Chapters 6 through 9 we have developed mathematical models for two of the key components in solar energy systems: collectors and storage units. In this chapter we show how other components can be modeled and how the component models can be combined into system models. With information on the magnitude and time distribution of the system loads and the weather, it is possible to simultaneously solve the set of equations to estimate the thermal performance of a solar process over any time period. These estimates (simulations) are usually done numerically and provide information on the expected dynamic behavior of the system and long-term integrated performance.
关键词： mathematical models,solar energy systems,simulations,thermal performance,collectors,storage units
更新于2025-09-16 10:30:52
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Solar Engineering of Thermal Processes, Photovoltaics and Wind || Solar Process Economics
摘要： In the first 10 chapters, we have discussed in some detail the thermal performance of components and systems and showed how the long-term thermal performance can be estimated in terms of the design parameters of the components. We also want to be able to assess the value of a solar process in economic terms. Given the performance, we need methods for making economic evaluations.
关键词： thermal performance,economic evaluations,solar process economics
更新于2025-09-16 10:30:52