The Efficiency of a household thermostat solar Water Heater model with two flat panel collectors and a double-glazed storage tank of 200 liters capacity was investigated experimentally. Water and glycol (antifreeze) are used as operating fluid in the Water Heater to be transformed into thermosyphon with free movement and increase the temperature of consumed Water. Water is not discharged during the test period. Flow temperatures of collector input and output, city Water temperature, Water temperatures at different points in the reservoir and ambient temperature for sunny days in the autumn in Tehran. Measurement and flow rate of the thermosyphon, thermal energy of the Water consumed and total Water Efficiency The aforementioned Heater has been calculated and the corresponding graphs are given over time. The results show that the highest Water temperature is 60 °C on sunny days and 50 °C on cloudy days. The overall Efficiency of the thermostat solar thermal Heater will be around 45درصد during the month of November 1396. The highest photovoltaic panel Efficiency in the sunny days is 13.5% in the autumn and 11.6% in the cloudy days, which is due to the decrease in Efficiency compared to the ideal conditions. The surface temperature of the panel is high.

The solar radiation energy is one of the clean, essential and renewable resources for future. Iran, having 300 annual sunny days, has such intrinsic potential and thermosyphon solar-electrical Water Heaters (TSEWH) are the simplest solar-thermal convertors. Despite their unique merits, they can not supply hot Water for domestic applications during cold period, so, an auxiliary backup system such as electrical resistance Heater (electrical element) is required. The reduction of consumed electrical energy by electrical element not only leads to decrease of electrical network load, but also enhances the solar Water Heater Efficiency and speeds up their application in the buildings sector. Careful scheduling the electrical element circuit via a timer key (timing mode operating) leads to reduction of auxiliary portion compared to the case that its circuit to be activated permanently (continues mode). Field results imply that, implementation the timer key to TSEWH has been considerable during cold period and reduced the consumed electrical energy as much as700kWh yearly and promoted its annual Efficiency from 46% up to 67%.

Domestic immersion Heaters used for heating cold Water are characterized by an electrical resistance heating element, which is encased in a tube and directly placed in it. The most common method for heating cold Water is the use of portable immersion rod Water Heater in an open bucket operating in operator control without a controller unit (thermostat). This paper performs an experimental evaluation of portable modifed conventional buckets of 10 l capacity. Out of ten portable modifed storages, the best three cases are discussed: non-insulated Open Plastic Bucket (OPB), non-insulated plastic bucket top surface covered with a transparent cover (CPB), and insulated plastic bucket closed with a transparent cover (ICPB). Maximum temperatures arising after two hours during OPB, CPB, and ICPB are 29. 82%, 47. 36%, and 21. 49%, respectively, compared to the initial temperatures (22. 8 C). At 14: 45 hour, CPB temperature reaches 35. 6 C, which is 17. 88% and 23. 61% higher than OPB and ICPB units. Due to the application of solar energy in CPB at 35{50 C, net saving increased by 12. 34%, 25. 76%, 40. 73%, 57. 93%, 76. 45%, and 97. 18% from 2017 to 2022 as compared to the saving in 2016.

Generally there are two ways for frost protection: active methods and passive ones. Passive methods should be carried out much earlier than the frost occurrence, for these methods are not the direct ways of frost protection but are the ways of avoiding and escaping from the frost. Active methods are the ways of frost protection that are carried out right before the frost or at the time of its occurrence. These methods include garden Heaters, spray irrigation, wind machines, etc. In the present study, 3 ways of frost protection namely fogger, Heater and fogger Heater were compared with the control treatment…. 

In this study, after fabricating a solar parabolic Water Heater, an efficient model is suggested to predict the Efficiency of the solar Water Heater system (SWHS). Artificial neural networks (ANN) can create logical relations among the input parameters and target (s). The Efficiency is trained as a function of the input parameters, when conditions are desirable to measure the data, a network-trained function can be used to predict the Efficiency of the solar system. The used data for the neural network analysis were measured by using experiments on a parabolic trough collector during four days in June. Variables such as solar radiation, ambient temperature and the output fluid temperature of the collector were considered as input parameters and the Efficiency of the solar parabolic Water Heater was used as the output neural network. Different ANN models are presented based on the various input parameters and neurons. The ANN6 model with a 4-10-1 structure, with a root mean square error (RMSE) of 0.0061 and regression coefficient for train data (Rtrainl) of 0.99995, is the most accurate among the presented models. By increasing the input parameters, the RMSE decreases and accuracy of the models increases. When experimental tests are not impossible in similar conditions, the presented model can help researchers predict the Efficiency of studied SWHS by saving time and cost.

In this research for the aim of optimizing the gas consumption, increasing the thermal Efficiency of a household gas Water Heater has been investigated numerically. The optimal design and configuration of the baffles in the middle tube of the gas Water Heater prevents the quick exit of the exhaust gases and consequently increases the retention time of the hot gases inside the middle tube and reduces the wasting of their thermal energy. The combustion process in the gas Water Heater is a chain process and completing this process occurs along its path in the middle tube. Therefore for obtaining the maximum thermal Efficiency, the numerical analysis of the combustion process and designing and configuration of the baffles inside the middle tube have been carried out and conducted simultaneously. The Ansys Fluent computational fluid dynamics code has been employed for the computational simulation of the combustion of the gas, the heat transfer from the contents of the middle tube into the Water tank and distribution of the velocity of the exhaust gases along their path inside the middle tube and around the baffles. Computational simulation of the problem under investigation has been carried out by considering different geometries and configurations of the baffles along the path of the exhaust gases. Numerical results show that the mass fraction of the methane gas and the carbon dioxide in the exhaust gases is negligible and consequently all of the methane gas has been consumed. The numerical results have been verified by the experimental results.

In the present work, a double-pass solar air-Water Heater has been designed for the first time to provide both hot air and hot Water for using in many engineering applications. The proposed solar collector can be a useful device for the purpose of heating spaces and providing domestic hot Water, simultaneously. It is like a conventional solar air Heater but five Water tubes are installed under the absorber plate with a large common surface area with the heated surface. The two-dimensional numerical simulation with the assumption of quasi-steady condition was done on a rectangular-shaped collector with a length of 1 m and a height of 0.128 m including five Water tubes by solving the continuity, momentum, and energy equations for the turbulent airflow by the COMSOL Multi-physics. The effect of forced convection Water flow inside the parallel tubes installed below the absorber plate is employed as a convection boundary condition in solving the air energy equation. Also, the convection boundary condition was employed on the boundary surfaces of the glass cover and insulation layer adjacent to the surroundings. Numerical simulations are carried out for the air and Water mass flow rates of 0.01 kg/s and 0.03 kg/s, respectively. While the solar heat flux lies in the range of 5001100 W/m2. In several test cases, high thermal efficiencies (69% to 74%) are computed for the proposed collector, whose value is much higher than a smooth duct solar air Heater operating under the same condition. A comparison is also made between the performances of double-pass and single-pass solar air-Water Heaters and a percentage of Efficiency increase about 6% was found. This value reached to 75% when this solar collector is compared with a conventional solar air Heater.

This paper presents a research on thermal Efficiency of home gas Heaters. Installing baffles inside the furnace and against hot product gas flow prevents rapid gas flow out of the chimney, causing to increase the residue time of flue gases. Therefore, instead of heat energy loss, the energy is transferred to the room, thereby increasing the thermal Efficiency of the gas Heater. On the other hand, installing these baffles increases pressure drop, which can cause incomplete combustion and pollutant formation. In this work, we used fluent software to simulate fluid flow and heat transfer of product gases for different suggested obstacle surface configurations, and studied its effect on the thermal Efficiency of gas Heaters. Obstacle configuration with the maximum thermal Efficiency is determined, built in workshop, installed and tested experimentally and its performance is shown to correspond with the computer simulation. Ultimately, the thermal Efficiency of the model 12000 of Donar-khazar gas Heater increased from 76.2 to 82.9% using this model.

Introduction: Electrical performance of solar cells decreases with increasing cell temperature, basically because of growth of the internal charge carrier recombination rates, caused by increased carrier concentrations. Hybrid Photovoltaic/thermal (PVT) systems produce electrical and thermal energy simultaneously. PVT solar collectors convert the heat generated in the solar cells to low temperature useful heat energy and so they provide a lower working temperature for solar cells which subsequently leads to a higher electrical Efficiency. …