Analysis of cooling cycles with clathrate energy storage

In this dissertation research, a prototype of a thermal energy storage facility, with an appropriate storage medium, that can be applicable in environmental control of residential and commercial buildings, has been investigated. A simulated heat pump cooling system which utilizes a refrigerant gas hydrate as a storage medium has been experimentally and theoretically analyzed. Numerous closed loop cycles using a clathrate in direct contact heat transfer with the refrigerant have been evaluated to verify the system operation and to evaluate the system components. The basic background of the direct contact heat transfer method in which heat transfer enhancement is achieved is investigated. The aim is to provide clear theoretical insights to the phase change of the storage medium (clathrate), and present a mathematical model that is compatible with the latent heat release rate.; A finite difference computer code utilizing the apparent heat capacity model has been developed to predict the experimental temperature fields inside an insulated cylindrical horizontal thermal energy storage tank as time progresses. Photographs have been taken at various intervals in order to investigate the crystal growth of the storage medium during the energy storage phase. Computer codes have been developed to acquire the raw data through a computer interface with transducers, and to evaluate the performance of the system from the data. The basis is an energy balance around each component of the system as well as calculations of the total system energy. The computer codes have the capabilities of evaluating different storage media with direct contact heat transfer process as well as simulating the transient temperature fields inside the storage tank. The experimental and theoretical results show that clathrate energy storage and direct contact heat transfer are technically feasible.