Micro gas turbine cogeneration system with latent heat storage at the University: Part II: Part load and thermal priority mode

A good cogeneration system should have high efficiency and good coordination. A micro gas turbine cogeneration system with latent heat storage was demonstrated at the University. Since there had been no cogeneration system with the latent heat storage under service condition, this system was the first demonstration and its characteristic was very important. The proper use of the latent heat storage system will save energy economically, store high energy density, reduce exhaust emissions, and save operational costs. A heat exchanger and an economizer were located in parallel downstream of a bypass dumper for exhaust gas. The latent heat storage tank was located downstream of 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 the University, the winter term heat demand from 6 pm to 7 pm was somewhat less than that from 8 am to 6 pm in 2010. We conducted a part-load operation from 6 pm to 7 pm to observe how it would respond to the heat demand. The heat supply from the cogeneration system during this time period was controllable with the heat storage. The heat supply from the system at the lowest power setting was larger than the heat demand, and thus was uncontrollable without heat storage. In Part I [1], a fixed operating schedule of the system was planned and demonstrated at the University. Total 407 charge/discharge cycles of the latent heat storage were repeated. The energy flow test of the system shows the importance of heat release source and total system design. In Part III [2], a temperature control schedule of the system was demonstrated in winter morning using a new programmable logic controller (PLC). If the more larger latent heat storage system will be developed in the future, it will be expected greatly that the temperature of the classrooms are kept more comfortable with less energy consumptions and less CO2 emission. (C) 2013 Elsevier Ltd. All rights reserved.