Hiromi Takeuchi

Remote Measurement and Heat Demand Control of CHP System With Heat Storage at Sapporo City University

Combined heat and power (CHP) systems are widely used to prevent global warming and reduce energy costs. Both high efficiency of the elements and good coordination of the systems are considered as the points to solve. A microturbine CHP with a latent heat storage system was demonstrated at Sapporo City University. The heat exchanger of the CHP and an economizer were located in parallel downstream a bypass-dumper of the exhaust gas. The latent heat storage tank was located downstream the economizer. The bypass-dumper released exhaust gas when the boiler water in the heat exchanger exceeded 90°C. It is very important to use the heat supply of hot water as much as possible. At Sapporo City University, the winter term heat demand from 6pm to 7pm was somewhat smaller than that from 8am to 6pm. We tested a partial load from 6pm to 7pm to observe how it would respond to the heat demand. The heat supply from the microturbine CHP from 6pm to 7pm was shown to be controllable with heat storage. The heat supply from the microturbine CHP at the lowest power was larger than the heat demand so without the heat storage it was uncontrollable.Copyright

Study on a PCM Heat Storage System for Rapid Heat Supply

A thermal energy storage system employing phase change material (PCM) for rapid heat discharge was studied numerically and experimentally. In the numerical studies, paraffin wax FNP-0090 (product of Nippon Seiro Co. Ltd.) was used as the PCM and was encapsulated in four different capsules (sphere, cylinder, plate and tube) for investigating the effects of geometrical configurations. The capsules filled with PCM were placed in a rectangular tank. Water was used as the working fluid in a rectangular tank. Water was used as the working fluid in the circulation system to discharge the storage tank. A one-dimensional model was used for solving the water temperature distribution along the flow direction in the tank and a conductive one-dimensional phase change model was used for simulating the solidification process of the PCM inside the capsules. The effects of the capsule diameter and shell thickness and the void fraction on the performance of the heat storage system were also investigated. Results shown include the variation of the outlet water temperature of the storage tank with time, the temperature and heat release distributions of the PCM along the flow direction in the tank at different times, etc. A plate heat exchanger was used as a heat storage tank for experimental study. FNP-0090 was filled into the channels (the space between two plates) of one side of the heat exchanger and water flowed in the channels of the other side of the heat exchanger. The effect of flow rate and initial temperature on the outlet fluid temperature and heat release was investigated. The numerical results and the experimental data agreed within 10%.Copyright