Showing 4 results for Thermal Energy Storage
Vahid Khalilzadeh Bavil, Javad Mahmoudimehr,
Volume 15, Issue 10 (1-2016)
Abstract
This study is concerned with optimizing the daily operation of a solar power plant equipped with thermal energy storage system (TES). The modeling is performed by solving a set of non-linear governing equations and is verified through comparison with the literature. "Maximum production period" and "maximum revenue" constitute the objectives of the optimization study which are first considered individually (as two single-objective problems) and are then considered simultaneously (as a multi-objective problem). Genetic Algorithm (GA) is employed as the optimization tool. The results of the first objective (maximum production period) shows 7 hours increase in the daily production time as a result of employing the TES system. This occurred through saving energy during the times of high solar radiation and using the stored energy for electricity generation during the times of low or zero solar radiation. The results of the second objective (maximum revenue) indicate 13.5% increase in the produced profit as a result of employing the TES system. This improvement was resulted from saving energy during the times of low electricity price and using the stored energy for maximum electricity generation during the times of high electricity price. Finally, in the multi-objective study, 5 hours increase in the production period and 8.1% increase in the revenue were simultaneously obtained as a result of a proper tradeoff between the two objectives.
Mohammad Saleh Barghi Jahromi, Vali Kalantar, Mehran Abdolrezaie,
Volume 20, Issue 7 (6-2020)
Abstract
In the current study, natural solar ventilation has been investigated aiming at reducing the consumption of fossil and thus, reducing greenhouse gas emissions in a hot and dry climate in which the behavior of various fluid variables (temperature, velocity, and flow rate) is considered in different conditions. Since solar radiation is not uniform throughout the day, passive solar ventilation is unstable. In this regard, the natural displacement flow in a solar ventilator with copper thermal absorber, double-glazed glass compartment to prevent thermal energy loss, as well as phase change materials for the storage of thermal energy has been investigated, experimentally. In the case of no phase change material, due to the creation of a suitable temperature difference, the panel has made the chimney effect possible for natural ventilation in some hours of the day, but in the early hours of the night, the temperature of the panel will be the same as the ambient temperature, and the chimney effect will not be available for proper ventilation. In a panel equipped with phase change materials, the system has acceptably been able to play an important role in reducing the temperature drop in the hours of the day with no solar radiation leading to a reliable air flow rate. In fact, the main purpose of using phase change materials in passive solar ventilation is the same effect, the use of excess energy in cases of energy shortages.
Alireza Etemad, Ashkan Abdalisousan, Mahdi Aliehyaei,
Volume 22, Issue 2 (1-2022)
Abstract
A significant portion of world energy consumption belongs to building sector, And HVAC systems have an important share in building energy usage. In this research, a novel HVAC system has been proposed which is based on three technologies of combined heating and power, ice thermal energy storage, and solar heating. The system is named CCHP-ITESS as an abbreviation of previously mentioned technologies. This system was modeled on a case study building in Tehran, to obtain energy consumption, costs, and payback results in comparison with conventional HVAC systems. In order to realize the effect of energy prices on the economical results, the same system and building were simulated for the city of Los Angeles,California,US. The results showed that both scenarios will lead to significant reduction in net source energy consumption, which is 36.87% reduction in Tehran and 40.28% reduction in Los Angeles. However, the system is not economically reasonable in Tehran because of the low energy prices and has a 39 years of payback period, but is absolutely feasible in Los Angeles with ab payback period of less than 3.5 years. As a result, application of this system is feasible in Los Angeles and not feasible in Tehran.
Vahid Ghamari, Hassan Hajabdollahi,
Volume 22, Issue 3 (3-2022)
Abstract
The design and optimization of multiple production systems, including systems that simultaneously generate heat, power and freshwater, play an important role in improving the performance of these systems. In this study, after modeling a multi-effect evaporative desalination system MED and simultaneous heat and power generation CHP, they are combined to meet the demand for heating, power and fresh water for a hotel. The purpose of this study is the thermoeconomic evaluation of the use of thermal energy storage TES tank in the combined system CHP + MED compared to the non-use of this tank. The strategy is applied every 24 hours of the two seasons. In optimizing this system, the annual cost minimization has been done as a objective function and using genetic algorithm. Optimal technical results in these systems show that the system CHP + MED + TES requires a gas turbine with a nominal capacity of 12% larger and a backup boiler with a nominal capacity of 7.14% smaller than the system CHP + MED. The optimal results of the economic comparison show that by using the thermal energy storage tank in the combined system CHP + MED, the annual cost is improved by 4.91%.
