Operation Modes and Economic Performance Study of 100kW Microturbine Building Cooling, Heating and Power Systems

Microturbines are one of the most promising DG (Distributed Generation) technologies for Building Cooling, Heating and Power (BCHP) systems. They have advantages over other kinds of heat engines in terms of atmospheric emissions, fuel flexibility, noise, size, and vibration levels. The characteristics of the overall microturbine BCHP system may be different under various system configurations and operation modes which depend on the consumers and outdoor conditions. In this paper, on the basis of the authors’ previous work, the various possible operation modes are discussed under different external loads. The optimal operation modes are suggested to the microturbine BCHP schemes considering the various energy demands of a hotel in Xi’an. In the later part of this paper, the thermodynamic analyses and economic performance of microturbine BCHP system based on the first and the second laws of thermodynamics are carried out. The results show that even though the BCHP cogeneration system has the better economic performance both from the first and second laws evaluation, the benefits are affected by the operation modes because of the load uncertainty. The influence factors on the performance, such as power rate, natural gas price, operation time, are analyzed and compared for microturbine and gas engine BCHP systems. With the increase of natural gas price, or with the decrease of power rate, the economic performance advantages of both microturbine BCHP system and gas engine system are weakened, and the longer the cooling time, the shorter the payback periods for the system.