Phd Degree / Doktora
Permanent URI for this collectionhttps://hdl.handle.net/11147/2869
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Doctoral Thesis An Experimental and Theoretical Study on the Improvement of Adsorption Heat Pump Performance(Izmir Institute of Technology, 2008) Demir, Hasan; Ülkü, SemraAdsorption heat pumps, which have considerably sparked attentions in recent years, have the advantage of being environmentally friendly and operating with heat sources such as waste heat, solar and geothermal energies as well as storing the energy.The present investigation covers working principle of adsorption heat pumps, a detailed literature survey on the performed studies, information about adsorption phenomena, experimental results of two differently designed and constructed systems, numerical simulation of heat and mass transfer in an annular adsorbent bed, and microcalorimetric study for obtaining isosteric heat of adsorption for water vapor-silica gel pair. The two intermittent adsorption heat pumps can operate without any leakage. The silica gelwater was employed as the adsorbent-adsorbate pair in both of the systems. The temperature and pressure in the evaporator, condenser and adsorbent bed were measured and the coefficients of performance, total entropy generation, the second law efficiency, specific heating and cooling power values were calculated based on these measured values for all of the representative cycles. The heat transfer area of the second designed adsorption heat pump is 550% greater than the first designed adsorption heat pump and this increase resulted in 170% and 200% of improvements in specific heating power (SHP) and specific cooling power (SCP) values respectively. The silica gel granules were mixed with small size metal pieces in order to accelerate heat transfer in the bed. Experiments were performed to measure the thermal diffusivity through the adsorbent bed in which adsorbent is mixed with metal pieces. It was observed that the mixing of silica gel grains with 10wt% of small size aluminum pieces increases the SHP and SCP values of the second heat pump by 250%.Doctoral Thesis An Experimental and Numerical Study on Heat and Mass Transfer in Adsorbent Bed of an Adsorption Heat Pump(Izmir Institute of Technology, 2012) Gediz İliş, Gamze; Mobedi, MoghtadaBecause of the limited conventional energy sources, the improvement of thermal heat pumps has gained attentions of researchers in recent years. Adsorption heat pump, which is a kind of thermal heat pump, can be directly operated with the low temperature heat sources such as waste heat, geothermal and solar energy. Although, adsorption heat pump has many advantages compared to the conventional heat pump, there are still many difficulties for its practical application. Adsorbent bed is one the most important component of adsorption heat pump. Heat and mass transfer in the adsorbent bed should be accelerated in order to attain a small sized, high powered adsorption heat pump. In this thesis, a theoretical and experimental study is performed on heat and mass transfer in an adsorbent bed. A detailed literature survey on the design of adsorbent bed is done. The designed adsorbent beds are classified, and their advantages and disadvantages are discussed. In order to analyze heat and mass transfer in an adsorbent bed, transport of adsorptive in an adsorbent particle should be well known. A theoretical study on heat and mass transfer in a single adsorbent particle located in an infinite adsorptive medium is performed to understand the effects of internal and external heat and mass transfer resistances. Heat and mass transfer equations for an annular adsorbent bed are derived for uniform and non-uniform pressure approaches and numerically solved to determine temperature and concentration profiles in the bed. These equations are also non-dimensionalized to reduce number of governing parameters. The non-dimensionalization of the equations yields important dimensionless parameters that can be used not only to describe heat and mass transfer in an adsorbent bed but also employ them during design of the bed. Furthermore, an experimental setup was designed and constructed to validate the obtained numerical results. The experimental results were compared with the solution of the numerical results and a good agreement was obtained between them.