Journal of Solar Energy Research
Volume:6 Issue: 4, Autumn 2021

The aim of the present work is to make maximum use of environmental potentials in order to save energy consumption and increase the quality of comfort in residential space through the design of buildings in accordance with the cold climate in Iran. Also, providing part of the heat needs of the building under study by solar energy is another way to reduce energy consumption. According to studies, and despite the fact that Iran has a high potential to use solar energy, so far no studies have been conducted on the climatic design of residential villas in cold climates with the approach of using solar water heaters. Also, the study of six different solar technologies to find the optimal system and also the one-year dynamic analysis of the optimal system are other innovations of the present work. In the present work, initially, with the help of the recommendations provided by Climate Consultant 5.5 software, a residential villa has been designed in accordance with the cold climate of Iran. Then, using TSOL 5.5 software, six systems based on solar heating and boiler have been examined to meet the thermal needs of the villa. After finding the optimal heating system, a one-year dynamic analysis was performed on it. By examining the climatic parameters, the strategies needed to ensure the comfort of the residents were implemented on a psychometric chart. The orientation of the building, the depression in the ground, etc. were among the suggestions to make the design of the villa compatible with the climate. The results of reviewing six solar heating systems showed that the solar system, including a hybrid tank with an internal heat exchanger, with the lowest number of collectors, had the highest heat efficiency and was able to provide 41.5% of the annual heat required by the villa.

Efficiency reduction of photovoltaic cells caused by increasing temperature, is an important issue that restricts their use in the middle of the day especially in summer. A new cost-effective method to increase the solar cell efficiency is presented to alleviate the problem. A combination of 40 fiberglass small cells are used in the form of a panel to perform the experimental tests. Water is used as absorbent of heat to reduce high temperature effects on the panel and the test results show that the panel efficiency is increased using the suggested method by amount of at least 16.8%. A 300W halogen lamp is regarded as the light source throughout the experiments.

In this article- we study devices that derive energy from natural process (sun, wind, winter, soil, etc.) and that are replenished constantly such as fans generating electric power and solar energy devices. However, all devices are exposed to damage over time resulting in the accumulation of the damage caused by climatic fluctuations (Every geographical area is characterized by bad weather characteristics that leave damage to the device; like wind, rain and humidity) that lead to the failure of the device. These devices receive energy directly from nature in order to supply it to other systems (mechanical, electrical, etc.). A failure of the device reduces electrical-mechanical production. The companies manufacture renewable energy devices and export them to other countries in various geographical locations. The devices are used to provide electrical current in these countries. These companies seek to develop long-term protection plans against the device failure. A failed device becomes ineligible even for recycling in these companies. Therefore, the cost of the device failure and forced replacement becomes too expensive for these companies. Because of this, companies tend to find the optimal time to replace the device shortly before failure to reduce the cost of failure. In this experiment we study a device that is subject to shocks and calculate the optimal time for preventive replacement of a said device. As an example a solar energy device exposed to shocks resulting from climate fluctuations. We place this device in three different geographical locations (desert, tropical, and temperate), and calculate the optimal time for preventive replacement of the device. Finally, the results from these three locations are compared.

Dynamic capacitor (DCAP), as a shunt power quality device, corrects the power factor of the load and reduces the total harmonic distortion (THD) of the source current. A novel control method was presented based on the model predictive control (MPC) to control a three-phase three-wire buck-type DCAP. The injected current of DCAP is the control variable, which must be controlled by two power electronic switches of DCAP. MPC controller minimized the absolute value of the difference between a reference current and a DCAP current in the prediction horizon. The reference current consisted of two distinct parts, i.e., reactive power compensator (RPC), and harmonic current eliminator (HCE), based on the fundamental component of the load current. Also, a prediction model (PM) was proposed to calculate state variables of the DCAP based on their previous values, state of the switches, and prediction values of the grid voltage. The proposed PM was extracted from the linearized differential equations of the DCAP. All DCAP components, such as capacitors and inductors of the inner and outer filters, were modeled in the proposed PM. Unlike the PI controller, the proposed MPC has fewer control parameters and can use in extensive operational conditions. The simulation results in MATLAB software showed the superiority of the proposed method compared with the even harmonic modulation (EHM) method on a three-phase DCAP.

The output power, energy, and exergy efficiencies of gas turbines significantly decrease by rising ambient temperatures during the warm weather periods. The utilization of evaporative inlet cooling in gas turbine cycles increases its performance, which is extremely useful when trying to meet the increasing electrical power demands and offsetting shortages during peak load times, especially in these warm periods. With this mind the present study focuses on the thermodynamics of a gas turbine equipped with wet compression system and integrated with air-film blade cooling, to address the importance gas turbine efficiency. The results of the investigated basic and modified cycles presents that for a turbine inlet temperature of 1400 oC, an ambient temperature of 45 oC, and a relative humidity of 15%, adding an evaporative cooler to a simple gas turbine cycle leads to an approximate 21% increase in specific work, from 331 to 273.7 kJ/kg air, compared to the simple cycle. The exergy analysis indicates that the highest exergy destruction occurs in the combustion chamber, owing to the large temperature differences and the highly irreversible exothermic chemical reactions.

The flat plate collector is the most famous and simplest type of solar collectors that is used as a water heater. In this study, a solar flat plate collector with triangular geometry and with zigzag and non-riser tubes was experimentally examined. To assess the collector, the ASHRAE standard was used in hot and dry climate conditions. The test site was located in southwestern Iran and was tested in the early months from March to June 2020. The measured parameters include the environmental and thermal parameters of the collector and the fluid, and the best data have been selected and presented. The results of the study showed that the collector had a suitable efficiency; the lowest recorded value was 32% and the highest was 58.9 %. Hence, It could be used as a solar water heating system in both domestic and industrial sectors. In the pressure drop testing, the results showed that in all flow rates used, the pressure drop in the collector was less than 0.1 bar. Also, the performance of the collector was presented based on environmental variables such as temperature and radiation, as well as fluid variables such as input temperature and flow rate.