Application Research On Efficient Utilization Of Waste Heat In Hotel Buildings

With increasing building energy consumption, the energy consumption of air-conditioning systems and hygienic hot water systems in hotel buildings are considerable. It's an important method for reducing the operating costs of hotel that bringing down the air conditioning energy consumption. However, there is waste heat not been used in buidings. We can reduce building energy consumption if we can make full use of the waste heat in buildings.This paper introduces the waste heat available in hotel buildings and discusses the waste heat in exhaust air and the waste heat dissipated from equipments. Because the enthalpy of exhaust air is lower than outdoor air in summer and higher than outdoor air in the winter, we can reduce fresh air load and air-conditioning load if we can preprocess the fresh air by the waste heat in exhaust air. Increasing the flow rate of fresh air in transition season will help to eliminate heat dissipated from equipments in rooms. The waste heat in equipment rooms is bad for stable operation of the equipments. We can not only reduce the energy consumption of hygienic hot water systems, but also save the initial investment and running costs of mechanical ventilation systems, if we can recycle the waste heat by heat pump for heating hygienic hot water.According to the efficiency of heat exchanger, we can determine the suitable conditions of outdoor air for heat recovery from exhaust air by considering energy consumption of fan. And it should be suppose to increase the flow rate of fresh air in transition season which can take advantage of the cooling action of fresh air. We have simulated the annual operation of heat recovery system of exhaust air. The simulation results show that total heat recovery system of exhaust air with variable air volume is suitable for hot-summer and cold-witer regions. With exhaust air heat recovery, the fresh air load can be redeuced by 22.7%-27.2%. It is an efficient measure to adope total heat recovery system and increase the flow rate of fresh air in transition season.By simulating mechanical ventilation system and heat pump system at different outdoor temperatures and different ambient temperatures, we analyzed the temperature variation of laundry room and made the control principle of the systems. Systems simulation results show that the mechanical ventilation system can not reduce the temperature below 30℃in the laundry room at most of the time and the temperature is volatile. Whereas, the heat pump system can effectively control the temperature of laundry room in the range of 28℃-31℃. And the efficiency of annual energy utilization of heat pump can reach 7.5 because the heat pump system can provide cooling capacity for the laundry room and heat the hygienic hot water at the same time. Therefore, recycling waste heat in equipment rooms by heat pump is feasible and energy-saving.