Application Study Of Absorption Heat Pump Technology In CHP System

A great amount of low-temperature cooling water is produced by thermal power plants. These cooling water haves great low-level energy but also relatively low temperature (only 10℃above the ambient temp), which made the recycling work really hard. Therefore, this part of water is usually discharged directly into the environment just to cause serious heat pollution as well as waste too much energy. According to statistics, circulating cooling water takes away 60 percent heat. If this part of low-temp heat energy can be recycled, it will bring significant economic, environmental and social benefits.Generally speaking, heat pumps are used to recycle low-temp exhaust heat. However, both the first-type absorption heat pump and the second-type absorption heat pump cannot supply hot water to the high-temp Cogeneration of Heat and Power (CHP) System. In order to overcome the shortcomings of the Absorption Heat Pump System (single running mode and incapability in high-temp heat supply), Combined First-type Absorption Heat Pump Unit is developed. This Combined Unit comes into existence just for the efficient recycle of low-temp exhaust heat resources produced by thermal power plant, and etc; and it achieves the combination with the city CHP System.This Combined Unit takes extracted steam (from turbine) as the driving (heat) power to recycle exhaust energy of the circulating cooling water. The energy recycled is the energy saved, which will help to cut down the need of extracted steam from turbine.At the beginning and ending of the heating period, the Combined Unit will work in low-temp mode; while at the heating peak, the Unit will run in high-temp mode, which will effectively help to improve the utilization ratio of the resource and equipments. The paper analyzes the circulation process of the Combined Absorption Unit in detail, on the basis of which heat calculation and heat transfer calculation are carried out. Meanwhile, Matlab language is used to program the calculation of the circulation. The program helps to realize the Process Simulation and Performance Analysis as well as provide methods and theoretical basis for technical studies of the Combined Absorption Unit.At last an economic analysis is carried out making use of technical indices as Primary Energy Ratio, Payback Period, and etc. The results show that the Combined Absorption Unit possesses an apparent advantage on recycling of low-temp exhaust heat. This technology successfully broadens the range of application of the Absorption Unit. The Coefficient of Performance can reach up to 1.6; and the Primary Energy Ratio is also improved by 30%. Furthermore, the unit is with an edge of low dynamic annual cost and short payback period. The calculated result shows that the present method can save about $1,290,000 every year for heating. The signnificance of resulting low phase energy is emphased again according to the conclusion.