Research On The Economic Cooling Parameter In District Cooling System

Because of high efficiency of energy utilization, easy maintenance,district cooling system aroused great concern. In recent years, China also began to introduce this cooling system, with the development of district cooling systems in China, there is also highlighted a number of issues in engineering practice, such as big initial investment, high cost of operation and maintenance, low efficiency of refrigeration. Thus it brings obstacles to promote district cooling system.in order to solve this problem, we need to consider the economic benefits, and the main factors influencing the economy of the system for a number of key parameters of the system including cooling radius, chilled water supply and return water temperature, chilled water velocity, etc. From the perspective of economic system to study the effect of these parameters on the economy and draw economic cooling parameter value.First, the paper describes the types of district cooling system and its components, according to the type of system to determine the initial investment of various components, and describes the types of district cooling cold source, the study the method for determining the cooling capacity of the unit. And describes a brief analysis of the impact of the district cooling system parameters on the system of the costs.Then, study the influence of system parameters on major operational equipment(eg refrigeration unit and pump) performance, analysis various parameters such as the supply and return water temperature, cooling water inlet temperature on the energy efficiency of the refrigeration unit based on the heat transfer principle, and calculate refrigeration unit operating costs. According to the pump performance curve analyzes several operating modes of the pumps and the performance of different modes of pumps, and calculate operating costs under different conditions of pumps.Secondly, study the cooling loss caused by the transmission and distribution network, highlighting the cooling loss caused heat transfer between pipe and soil, and pump operation. And calculate the temperature rise caused by cooling loss, analyze their impact on system investment.Finally, in order to solve the district cooling system of optimum cooling velocity radius and economic problems, according to the user distribution characteristics of the district cooling system, simplifies the system cooling load distribution and pipeline distribution, using life-cycle cost approach to economic best as the goal, and establish the objective function of district cooling system economic cooling parameters, combined with engineering examples for some of the parameters of the objective function evaluation, and study electricity prices, cooling water velocity, temperature difference between supply and return water, and user load density and other factors on economic impact of the district cooling system, and calculate parameters economic cooling parameters for different conditions of district cooling system, such as economic cooling radius and economic velocity.The stuy results show that economic cooling radius decreases with the increases of the electricity price,and increases with the load density increases,the flow rate increases with the cooling economy radius increases,and increases with the supply and return water temperature decreases. In defined cooling defined radius, the larger of the temperature difference between supply and return water, the more economy of district cooling system as possible. The stuy findings can significantly improve the economics of district cooling systems,and provide theoretical basis and technical guidance for district cooling system designed, have great significance.