The cash balance equation and the corresponding exergy balance equation of the gas boiler system arecg0Exg0+ceExei+Zi=cgiExgi,(8a)Exg0+Exei+Exhgi?Exgdest=Exgi.(8b)The heat load of 300,000 square meters of residential district is 12MW; we can configure two 7MW gas boiler [10] systems for district sellekchem heating. The related formulas are as follows:B1=3.6��106��Q1�Ǧ�?Qar?net��1.02,Exg0=B13600(1?Tg0Tg)?Qar?net,��g��=ExgiExg0+Exei��100%,(9)where B1 is the gas consumption of the boiler system, m3/h; �Ǧ� is the thermal efficiency of the gas boiler, which is 88% when the capacity of the gas boiler is more than 7MW; Qar?net is the low calorific value of the gas, 35530kJ/m3; 1.02 is the additional coefficient of the hot water heat loss through the heat exchanger station; Tg0 is the exhaust gas temperature, 298K; Tg is the combustion temperature, 573K.
After calculation, we can get the exergy efficiency of the gas boiler system ��g�� being 43.9%.3.3. Annual Heating Cost Analysis of RWSHPSThe output exergy costs [11] of energy conversion system are composed of the cost of energy and nonenergy costs. The heat exergy and electricity exergy are energy costs, but the annual cost of the system is nonenergy cost. The total cost of the system is the sum of energy cost and nonenergy costs:Cpr=CEn+Za.(10)Thermoeconomics cost includes not only the external energy exergy cost but also the cost of investment and operation management costs in the process of production; it reflects the economic efficiency of the process of the production.3.3.1.
Energy Cost of the RWSHPS System operating costs mainly include the electricity cost of each part; water charges within the secondary network are not considered here. There are several known conditions on the energy cost calculation.In Shijiazhuang, one heating season contains 120 days, from 15 November to 15 March, According to running experience, in the period of 15 November to 15 December and 15 February to 15 March, the loading rate of the system is 0.5, and in the last two months of the heating period, one is at full capacity, and the loading rate of the rest GSK-3 of the month is 0.8.The project belongs to the livelihood projects; the Reclaimed water entering into the system is free of charge; namely, the cost of logistics exergy c0 entered into the system is equal to 0.The electricity price is 0.52 yuan/(kWh), calculated in accordance with the public electricity prices; the data are listed in Table 1.Table 1Energy costs of RWSHPS.3.3.2. Nonenergy Cost of the RWSHPS Annualized cost includes the investment costs and management costs of the system.