Optimization design of cooling water temperature and temperature difference in central air conditioning systems

In view of the cooling water temperature difference in central air conditioning systems typically setting at 5℃, from the visual angle of economic and technology, establishes mathematical models to analyse the effect of the cooling water temperature and temperature difference on primary and operating costs of the cooling water systems. Taking the minimum sum of annual depreciation cost and operating cost as object, analyses and calculates the effect and educes the relationship between the optimum cooling water temperature and temperature difference and the price of electricity. The results indicate that on the basis of satisfying the demand of minimum flow rate of chillers, the cooling water temperature difference should be designed as large as possible if the price of electricity is less than 21 Yuan/kWh; and that the optimum cooling water temperature goes as low as the cooling tower can afford on the condition of other parameters of cooling tower being constant.