جستجوی مقالات مرتبط با کلیدواژه "کلکتور صفحه تخت" در نشریات گروه "فنی و مهندسی"

The main part of the solar heating system is the solar collectors, the most common of which are the flat plate collector and the evacuated tube collector. In domestic use, solar hot water systems based on flat plate collectors are used more because of their low cost and minimal maintenance. Also, the outlet temperature of the collector corresponds to most domestic hot water needs. Solar hot water systems' performance varies with environmental conditions changes (atmospheric temperature, solar radiation, wind speed). This article modeled an indoor solar hot water system using TRANSYS software. This modeling is the development of a solar hot water system model based on an active flat plate collector. The developed model can predict the performance of the solar hot water system for different climatic and seasonal changes in the year. The system's long-term performance for Iranian weather conditions is evaluated and presented in the paper. Performance parameters such as the functional energy efficiency of the collector and hourly and monthly thermal efficiency are presented and discussed. Among the simulation results, it can be mentioned that the solar hot water system with a collector area of 5 square meters can meet more than 70% of the 400 liter needs of a household in Ahvaz, Iran.

In this paper, a forced-circulation solar water heater system is simulated for different hot water consumption profiles using flat plate collectors as well as evacuated tube collectors. The profiles studied are the actual samples of hot water consumption profiles for different commercial centers and institutions. Dynamic simulation outputs of system thermal performance are used as economic analysis inputs of solar water heater to evaluate the effect of hot water consumption profiles on the economic performance of system. The results show that profiles allocating large amounts of hot water consumption from 6 to 10 a.m. increase the cost of providing required energy for the auxiliary system. As a result, the system payback time increases. According to the simulation findings, changing profiles in the system can moderately increase the annual life cycle saving by 61% and 31% for the flat plate and evacuated tube collectors respectively.

Solar collectors play key role in solar thermal systems and their efficiency has more effect in the system performance. The shape and geometry of solar collectors is an important factor to increase their efficiency. In this paper, two collectors, a 3-D stationary solar collector which is called solar conical collector and flat plate collector has been investigated. These two solar collectors have the same absorber area and designed and tested in the same conditions. The performance of solar collectors was experimentally studied by the use of ASHRAE standard. Experiments were performed with water as a working fluid in the south of Iran with deference outdoor conditions and the best data has been selected. The results show that the average of thermal efficiency of a solar 3-D collector is about 59% while this value was about 53% for flat plate collector. The performance of both collectors versus radiation, flow rate, temperature variation was studied and the experiments indicated that the efficiency of the 3-D conical collector has better than the flat plat collector.

It is the aim of this paper to determine the parameters affecting thermal performance of flat plate solar collectors. As a first step, theoretical models for different configurations of a flat plate collector are introduced. These include riser tubes below the absorber plate, tubes above the absorber and tube in between.
A comparison is then made between the theoretical results and real experiments which were implemented in solar energy laboratory at South Tehran Branch of Islamic Azad University.
According to the results, the maximum absorbed energy is for the case where tubes are below the absorber plate. Decreasing the distance between the riser tubes , applying low emissivity glass and increasing insulation thickness are among the parameters which increase collector thermal efficiency. In addition, decreasing the pressure of the gas between the absorber plate and collector glazing increase collector efficiency. Insulation material and working fluid also affect the collector thermal efficiency.

Nowadays, in order to heating water in low-temperature residential applications, flat plate solar water heater is widely used. In this paper, we aim to discuss the thermal performance of MWCNT-water nanofluid in a flat plate solar water heater. The nanofluid has been prepared in solid volume fraction of 0.05% and its thermal performance has been experimentally investigated. In order to make a dispersed and stable nanofluid, Sodium Dodecyl Benzene Sulfonate surfactant has been used. The results showed that using the nanofluid has a considerable effect on improvement of the performance of the flat plate solar water heater. Furthermore, the increase of the system’s performance under natural circulation is much higher than that of forced circulation.

Small-scale cogeneration systems, by using the micro-turbines, have provided required electricity and heat in Hotels and residential complexes over the years. Hotels with CCHP system has higher energy efficiency compared to other energy systems, since usescogeneration waste heat for heating and cooling applications. The main advantages of cogeneration systems are reduction in fuel consumption, lower greenhouse gas emissions and environmental pollutions. In this study, it was tried to further introduce these systems, their function and economic analysis at the national level, in order to extend their usage in different places such as office, industrial, commercial and residential complexes. One method is to use solar radiation to provide part of energy required for water heating. Energy consumption pattern in a large hotel over the years was considered and economic analysis was performed for different energy consumption scenarios. Payback period were computed of each scenario, in order to make a positive attitude towards the use of cogeneration systems utilizing solar energy.

Regarding to the increase of cost and consumption of the nonrenewable energies such as natural gas and electricity, using renewable energies such as solar energy reduces the consumption of nonrenewable energies. In this research, at first, a regenerative organic Rankine cycle with flat plate solar collector as energy source is simulated and the effects of different parameters such as turbine inlet temperature, turbine inlet pressure, condenser temperature, solar collector area, environment temperature and solar radiation intensity on energy and exergy efficiency of system under seven organic fluids are investigated. Finally, system optimization with mentioned parameters is taken related to objective function of energy efficiency and objective function of exergy efficiency. The results of optimization illustrate that between the chosen fluids: R141b, R113, R32, R134a, R12, R717, R290, the highest and lowest performance belong to R113 and R32 respectively.