جستجوی مقالات مرتبط با کلیدواژه « تولید همزمان برق و حرارت » در نشریات گروه « مکانیک »

Today, the use of integrated (hybrid) energy supply systems due to the reduction of electrical and thermal losses, better control of distributed generation sources to better feed the system loads, reduce the emission of environmental pollutants and increase the reliability of load supply even in the event of failure , Is on the rise. In this research, an optimal and economical method to design a hybrid energy supply system based on CHP sources and photovoltaic sources to combined heat and power required by consumers, taking into account various costs such as initial investment cost, operating cost, Fuel costs, maintenance costs and various technical constraints such as production limitations of each source, power exchange with the upstream network and maintaining power balance are presented. Inheritance (genetic) algorithm has been used to solve the resulting optimization problem due to its good ability to solve complex problems with a large number of variables. The results show that in designing the system to supply electricity and heat, the system connected to the grid requires lower operating costs than the other two modes and the possibility of exchanging power with the upstream network due to the purchase of electrical power required from The network significantly reduces system costs in the event of a shortage of photovoltaic panels and the sale of power to the grid during off-peak hours and overproduction, as well as during peak hours of the upstream grid, where electricity prices are higher.

In this research, thermodynamic modeling of a combined production cycle of heat and power is performed based on a solid oxide fuel cell for building sector applications. Initially, the thermodynamic assessment is explained by introducing the mentioned cycle and its respected modeling technique. Then, cycle simulation is performed using Cycle Tempo analytical software by simultaneously solving the mass, energy, and electrochemical equilibrium equations. Parametric analysis of the main characteristics influencing the performance of the cycle is assessed, and the appropriate operating conditions are determined after presenting the performance results. The results show that using this model, electric power of 14.00 kW, thermal power of 4.56 kW, heat to power ratio of 32% at net electrical efficiency of 58.5%, and total efficiency of 77.3% is achievable. These results also confirm the attractiveness of the proposed systems over other electricity and heat cogeneration technologies, which are based on gas engines or gas micro turbines. The system is highly recommended in administrative buildings and warm and warm/moderate climates considering the functionality of the proposed system in different heat to power ratios.

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.

One of the most suitable places for the implementation of cogeneration systems (CCHPs) are hospitals . The high and continuous of electricity, heating and cooling loads in these places have caused the use of this type of system to be of great attraction. The low tariffs for energy carriers in government hospitals have caused the private sector to refrain from investing directly in this sector due to lack of economic justification. In this study, which was performed in a typical hospital, as one of the most suitable places for construction of the CCHP system, the capacity has been estimated to 2.4 MW power plant based on two 1.2 MW gas engines. In this project, it is anticipated that by utilizing the waste heat of gas engines in the supply of heat and power to the hospital, the energy conversion efficiency could be increased from 42% to 56.4%. In this study, different solutions have been introduced in order to eliminate the obstacles of the ruler in attracting this amount of investment .

The Cement industry is one of the highest energy consuming industriesin the world. The cement industry consumeda large part of total energy. A large portion of this energy iswasted byexhaust gases fromthe chimney and ventedto the atmosphere. With using the time value of money in payback period, in this study, thefeasibility of using hot chimneygases from BojnourdCement Company chimneys to cogenerate heat and power system has been investigated. Theminimum temperatures of the hotgases from the chimney NO. I and II were 130oC and 250oC, respectively. The thermal energy of the chimney gases wasused to convert inlet water stream to superheated vapor. The results revealed that using an energy recovery system at this plantand generating electricity, it could be possible to return the investment in 2.26 years. Finally, thetemperature of theexhaust gases from combined heat and power generation system reached to 112oC and 104oC.

The growing demand of energy coupled with decreasing in fossil fuels supplies, on the other hand, environmental pollution of fossil fuels and harm effect of it on lives of humans and other creations in world led to research in situated energy resources. The cogeneration or combined heat and power generation (CHP) and distributed generation could be the key strategy to achieve reduce energy consumption and environmental pollution. With considering this facts, thermophotovoltaic (TPV) technology could be very useful. Thermophotovoltaic is a system to convert into electrical energy the radiation emitted from an artificial heat source (i.e. the combustion of fuel) by the use of photovoltaic cells. A domestic gas furnace based on this technology can provide the entire thermal need of an apartment and can also contributes to satisfy the electrical demand. In this research, the initial studies and fundamental concepts in area of thermophotovoltaic and comparison of this technology with other direct electrical generation technologies are presented. Finally the potential of thermophotovoltaic technology for satisfy building thermal and electrical energy needs will be investigated.

In the present research, the effect of ambient temperature on a distributed generation (D.G.) gas engine generator performance in hot and dry climate of Yazd province is studied. The gas engine is an internal combustion engine which is coupled with a 1 MW generator and engine cooling system is performed by a fan cooler. Ambient conditions such as altitude above the sea level, temperature and humidity are strongly effective on the gas engine performance and as a result affect the system electrical power output. In this paper, the effect of changes in ambient temperature on gas engine performance and heat and electricity generation in summer and winter weather conditions is studied. Results show that in summer the ambient temperature highly affects the system performance such that, in the ambient temperatures higher than 40 ºC, the electrical power output decreases approximately 12% for every 5℃ increase in ambient temperature. In winter and ambient temperatures lower than 15℃, the effect of ambient temperature on the system output is less significant than summer season. In combined heat and power (CHP) cases, these changes are effective on generated heat rate. According to results, in economic and technical evaluation of these systems the effect of ambient temperature on power and heat generation must be considered and backup must be provided if needed.

Using the energy of the high-temperature flows, one of the most effective ways to save the ‎energy in industries. In this paper, the technology of combined heat and power generation in the ‎cement industry was investigated. For this purpose, the thermal energy in the hot exhaust gases ‎from the furnace clinker was used. The results showed that when using the hot exhaust gases ‎from the furnace with a temperature of 570 C, 57.9 kJ/s works was done by turbine. In addition, ‎the temperature of the hot exhaust gases from the process reached to 100 C and this could be ‎used in heating purposes such as: production of hot water, space heating and dehumidification of ‎cement.‎

The aim of this paper is to investigate cogeneration of electricity and hot water. In the presented design، thermoelectric module has been devised in the path of heat transfer from solar heat absorber surface to a water reserve. Besides، Fresnel lens is employed to concentrate sunlight as well as to reach justified temperature by the means of thermoelectric modules. The Fresnel lens belongs to a class of point focus lenses، which its dimension is 30*30 cm2. In order to optimal use of the thermoelectric capacity، it is proposed to devise an array of Fresnel lenses which can transfer heat to the thermoelectric module via mineral oil. The results show that approximately 186W thermal power and 6W electric power can be obtained by use of a thermoelectric module (type TEP1-12656-0. 6) and 6 Fresnel lenses. Results indicate that the maximum thermoelectric power generation is 1. 08W under radiation intensity of 705. 98 W/m2. Moreover، thermal efficiency of system is about 51. 85%.