Sharif Digital Repository

In this study the first and the second laws of thermodynamics are evaluated for a single effect absorption chiller. Entropy generation and COP are selected as the objective functions and their variations are studied by varying the generator temperature for various condensing temperatures. For this purpose, the enthalpy and the entropy data of the super-heated steam, saturated steam and the saturated water are formulated in the mathematical equations. Also to provide the required steam of generator, prime mover in the form of internal combustion engine is applied and its partial load conditions are analyzed. A residential tower is considered as the case study for selecting the proper prime... 

Total site integration offers energy conservation opportunities across different individual processes. It also helps for design as well as optimization of the central utility system. It gives massive energy-saving opportunities. The large industrial CHP sites generate heat and power simultaneously. These sites have different steam levels at different pressures which are used for power generation via steam turbines and also directly for satisfying process heat demand. There are many sites requiring cooling demand in hot seasons. In this article, integration of a LiBr/water absorption chiller in a CHP site has been investigated until its cooling demand is satisfied. Low pressure steam at 3 bar... 

In this study, an experimental investigation of using the radiative cooling potential in a solar still was studied. Instead of using an auxiliary radiative panel, an integrated collector was utilized for both processes of absorption of solar radiations and emission of infrared radiations for radiative cooling. At night-time, the coldness was stored in the PCM inside the PCM-condenser. While during the day, the water was evaporated in an evaporation tank, the produced vapor was directed to the PCM-condenser and the air cooled-condenser. Different condenser configurations were tested to evaluate the effect of radiative cooling on daily yield and solar still efficiency. The lower temperature of... 

The yearly thermo-economic performance is dynamically investigated for three solar heating and cooling systems: solar heating and absorption cooling (SHAC), solar heating and ejector cooling (SHEC), and heating and solar vapor compression cooling (HSVC). First, the effects of important design parameters on the thermo-economic performance of the systems to supply the heating and cooling loads of the building are evaluated. The systems are parametrically analyzed with the weather conditions of Tehran, Iran. The results show that the life cycle costs (LCC) of the SHAC and HSVC systems are alike and much lower than those of the SHEC system. The HSVC system exhibits the best performance from... 

In this article, a solar absorption chiller used in MehrAbad region of Tehran, Iran is optimized with exergoeconomic principles and genetic algorithm. After optimizing, a storage system with Phase Change Material technique (PCM) is designed for this optimum configuration for supporting system when sunshine is not received adequately, especially at night. Exergoeconomic analysis is based on finding some ways to improving the performance of a thermal system considering economic constrains. In this study, the exergoeconomic optimization is applied for LiBr-water absorption. The results show that total investment cost of main system, the whole of system except storage system, has increased... 

The main propose of this research is providing a tool for suitable modeling, increase efficiency and decrease construction cost of solar absorption chiller. At first, the solar absorption chiller is modeled by the thermodynamic laws. Then, this model is converted to the new standard mathematical programming model with considering all technical and economic constrains. This mathematical model is optimized by Genetic algorithm (GA). After applying GA, optimized parameters of chiller heat exchanger designing and its electricity consumption are calculated. These parameters consist of heat exchanger effectiveness, heat transfer cross section area, heat transfer coefficient, efficiency of pump and... 

Combined cooling, heat, and power (CCHP) system offers numerous potential advantages for the supply of energy to residential buildings in the sense of improved energy efficiency and reduced environmental burdens. To realize the potential for being more beneficial, however, such systems must reduce total costs relative to conventional systems. In this study, a linear programming optimization model was presented for optimum planning and sizing of CCHP systems. The purpose of the model is to give the design of the CCHP system by considering electrical chiller and absorption chiller simultaneously in economic viewpoint. A numerical study was conducted in Tehran to evaluate the CCHP system model.... 

The yearly thermo-economic performance is dynamically investigated for three solar heating and cooling systems: solar heating and absorption cooling (SHAC), solar heating and ejector cooling (SHEC), and heating and solar vapor compression cooling (HSVC). First, the effects of important design parameters on the thermo-economic performance of the systems to supply the heating and cooling loads of the building are evaluated. The systems are parametrically analyzed with the weather conditions of Tehran, Iran. The results show that the life cycle costs (LCC) of the SHAC and HSVC systems are alike and much lower than those of the SHEC system. The HSVC system exhibits the best performance from... 

Solar systems are the most promising technologies to reduce building energy consumption. In recent years, one of the popular solar technologies is building integrated photovoltaic-thermal collectors, because of profitability and no need for separate architectural space. In this study, a new combination of glazed building integrated photovoltaic thermal solar collectors and an absorption cooling system, as a trigeneration system, to provide thermal and electrical energy demands of a case study residential building, is proposed. Dynamic simulation of the proposed system is performed using the TRNSYS-MATLAB co-simulator. Because there is no model for the glazed photovoltaic thermal solar... 

In the present study, exergoeconomic optimization of a trigeneration system for cooling, heating and power purposes has been carried out. The system is made up of air compressor, combustion chamber, gas turbine, dual pressure heat recovery steam generator and absorption chiller in order to produce cooling, heating and power. The design parameters of this study are selected as: air compressor pressure ratio, gas turbine inlet temperature, pinch point temperatures in dual pressure heat recovery steam generator, pressure of steam that enters the generator of absorption chiller, process steam pressure and evaporator of the absorption chiller chilled water outlet temperature. The economic model... 

In this paper energy, exergy and thermoeconomic analysis of a combined cooling, heating and power (CCHP) system has been performed. Applying the first and second laws of thermodynamics and economic analysis, simultaneously, has made a powerful tool for the analysis of energy systems such as CCHP systems. The system integrates air compressor, combustion chamber, gas turbine, dual pressure heat recovery steam generator (HRSG) and absorption chiller to produce cooling, heating and power. In fact, the first and second laws of thermodynamics are combined with thermoeconomic approaches. Next, computational analysis is performed to investigate the effects of below items on the fuel consumption,... 

During the last decades, the adoption of more strict safety and environmental regulations, as well as a rise in energy costs, sparked an increasing interest in the design of renewable energies systems, particularly solar systems, to supply both electrical power and heat. Because of their capability to simultaneously supply both electricity and heat, concentrating photovoltaic-thermal and thermoelectric hybrid systems have recently attracted scholarly attention. In this study, a detailed three-dimensional computational model of a novel concentrating photovoltaic-thermal solar system combined with thermoelectric modules in an integrated design with a triangular absorber and corresponding...