Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Modeling and Analysis of Heat Pump Integrated Pv-Wind Systems for a Commercial Greenhouse(01. Izmir Institute of Technology, 2023) Özcan, Zeynep; Çağlar, Başar; Bilir, LeventThis thesis focuses on modeling and simulating renewable energy (RE) systems that include photovoltaic (PV) panels, wind turbines (WT), and air source heat pumps (HP) for meeting the heating load of a commercial greenhouse (GH) in the agricultural zone in Dikili. Five different energy systems scenarios, namely (i) PV-HP, (ii) PV-WT-HP, (iii) WT-PV-HP, (iv) WT-HP, and (v) only HP were considered. For all scenarios the mismatch between the load and the generation was covered by grid. The second and third scenarios differ from each other based on the number of PVs and WTs. The design of the greenhouse was made with SketchUp and TRNSYS software based on dimensions of the greenhouse. According to the weather data and greenhouse parameters, solar radiation calculations were made, and the greenhouse system was modeled by MATLAB software. The annual heating and cooling demands of the designed greenhouse and electricity generation by PVs and WTs were calculated on an hourly basis. The heating and cooling loads were found to be 5,922,015 and 11,014,446 kWh/year, respectively. Since the maximum power output by RE for the reserved area is not sufficient to meet the cooling load, the cooling process was excluded. Economic and environmental analyzes were made. The first scenario including 5,271 PV panels and 20 HPs was found to be the best scenario. Net Present Value (NPV), Levelized Cost of Energy (LCOE) and CO2 savings of the related scenario were calculated as $547,440.40, 0.080146 $/kWh and 1,270.96 t.Master Thesis A Study on Cop Improvement of a Household Refrigerator by Using an Adsorption Heat Pump(Izmir Institute of Technology, 2015) Arslan, Gizem; Barışık, Murat; Mobedi, MoghtadaThe thesis aims to increase the coefficient of performance of a domestic type household refrigerator. A household refrigerator is a kind of mechanical heat pump which works based on the vapor compression cycle. On the other hand, adsorption heat pump is a thermal heat pump and it can directly operate with any kind of third energy source such as solar, waste heat. The heat released from the condenser of a mechanical heat pump provides the desorption of the adsorbate in the adsorbent bed and helps the transfer of the adsorbate to the condenser of the adsorption heat pump. Then, the adsorbent bed which has low level adsorbate concentration provides the evaporation of the adsorbate in the evaporator and generates a cooling effect. By this way, an additional cooling effect can be generated without the increase of energy consumption of refrigerator. In this thesis, a detailed literature survey on the combination of hybrid cooling systems is done. The suggested hybrid cooling systems are classified, and their advantages and disadvantages are discussed. In order to analyze heat and mass transfer of an adsorption heat pump, different conditions for adsorbent bed design are studied, theoretically. To design an adsorption heat pump the effects on the heat and mass transfer should be well known. Theoretical studies on heat and mass transfer in a rectangular adsorbent bed is performed to understand what can be effected on the heat and mass transfer in an adsorbent bed. Heat and mass transfer equations for a rectangular adsorbent bed are derived for non-uniform pressure approaches and numerically solved to determine temperature and concentration profiles in the bed with using Comsol Software. Furthermore, our CFD program coded in FORTRAN language. The code is used to validate the obtained results from Comsol. An experimental setup was designed and constructed in the light of these numerical studies. The enhancement of performance of a household refrigerator is calculated by using an adsorption heat pump.Master Thesis Determination of Characteristics of Adsorbent for Adsorption Heat Pumps(Izmir Institute of Technology, 2013) Sayılgan, Şefika Çağla; Ülkü, SemraAdsorption heat pumps, which are environmentally friendly and operating with thermal sources, have gained attention in recent years. Although they have higher primary energy efficiency than traditional heat pumps, adsorption heat pumps require improvements due to the low COP and SCP/SHP values. The selection of appropriate working pair, the determination of adsorption equilibrium and kinetics of the pair is quite important in the design of adsorption heat pumps. In this study, the working pairs used in adsorption heat pumps were discussed, and the models used in adsorption equilibria and kinetics were explained. In the experimental part, the effect of the adsorption and desorption temperatures on adsorption capacity and mass diffusivity were investigated. Type RD silica gel-water and zeolite 13X-water were selected as working pairs in the adsorption experiments. Accordingly, two volumetric systems were constructed; adsorption experiments were conducted and pressure changes were recorded against time. The experimental studies showed that the adsorption capacity was decreased with increasing adsorption temperature and with decreasing desorption temperature, and zeolite 13X-water pair had higher adsorption capacity than type silica gel-water pair under the same conditions. Type II and Type I isotherms were observed for type RD silica gel-water pair and zeolite 13X-water pair, respectively. The effective diffusivity of zeolite 13X-water pair was found in the range of 2x10-8-9x10-9 m2/s for the short time period and in the range of 7x10-10-10-8 m2/s for the long time period. In addition, it was seen that the effective diffusivity was effected from the initial adsorptive concentration and the effective diffusivity was decreased with increasing adsorbate concentration. This may be related to the effects of the heat transfer resistance, surface resistance or hydration and migration of the cations in the structure of the zeolite 13X.Master Thesis A Study on Isotherm Characteristics of Adsorbent-Adsorbate Pairs Used in Adsorption Heat Pumps(Izmir Institute of Technology, 2011) Yıldırım, Zeynep Elvan; Mobedi, Moghtada; Ülkü, SemraAdsorption heat pumps are promising systems due to their ability to recover heat at low temperature levels and to provide cooling and/or heating effects. It has advantages such as using renewable energy sources, being environmental friendly, having no vibration and lower operation costs. In this study, the most common pairs used in adsorption heat pumps were reviewed and their thermophysical and adsorption behaviors were discussed. The adsorption equilibrium phenomena were explained in details. The different experimental methods for determination of adsorption equilibrium for pairs were explained and compared. The change of heat of adsorption according to the varying adsorbed amount was studied numerically for two different equilibrium equations. It is found that, the heat of adsorption for pairs fitting Dubinin-Astakhov equation has a decrease with increasing adsorbed amount, while the heat of adsorption for pairs fitting Freundlich equation does not depend on adsorbed amount. A numerical study was performed to investigate the performances and cooling capacities of three different adsorption chillers for six different pairs. The results showed that when S40 silica gels - water pair is used, the chiller cooled with low temperature source gives the highest performances.In the experimental section of the present study, a volumetric setup was designed and constructed. Experiments were performed for a conventional pair of silica gel - water. It was observed that the maximum adsorption capacity of the experimented silica gel -water pair was 21% (kg water vapor /kg silica gel) at 35 °C, 19% (kg water vapor/kg silica gel) at 45 °C and 11% (kg water vapor /kg silica gel) at 60 °C.