Analysis and optimization on life-cycle cost of surface water source heat pump system in an industrial plant of Chongqing

Establishes a mathematical model of life-cycle cost (LCC), calculates and analyses LCC values of both surface water source heat pump system and conventional heating and cooling systems in the industrial plant. Analyses the composition and characteristics of energy consumption. The results show that the heat pump unit and chilled water pump consume a larger proportion of energy, which are 76.2% and 12.9% of energy consumption of the whole surface water source heat pump system respectively. Based on LCC, analyses the influence of load share mode of multiple parallel units on COP of units in different load rates. The results show that on the condition of the steady temperature differences between supply and return water for both chilled water and the water source, two units share the load evenly when the part-load rate is less than 28%, and four units share the load evenly when the part-load rate is greater than 28%, then the system LCC reaches its minimum value at 28.575 million yuan. Meanwhile, the system LCC reaches even smaller value at  28.259  million yuan when the chilled water pump is under frequency conversion control.