High Precision Constant Temperature Circulate Cooling System Experimental Research Based On Semiconductor Refrigeration Technology

The traditional high precision constant temperature control system mainly take the compressor as the temperature control device, but the compressor can’t start at zero and the start and stop of compressors will bring great fluctuation to the temperature control system, so as to affect the accuracy and stability of temperature. Therefore, a high precision constant temperature circulating cooling system based on semiconductor refrigeration technology (abbreviated as HPCTCSRT) was proposed in the paper. The technology mainly took the traditional mechanical compression refrigeration as the auxiliary, and the semiconductor refrigeration is precisely regulated as the core of the cooling capacity, the technology is a high precision control system to maintain the temperature in a precise environment. Based on the reasonable selection of system components, a 8kW precision constant temperature water chiller and a 3kW semiconductor refrigeration chiller were successfully developed. The units were tested under different conditions. The experimental results and analysis were as follows:Precision constant temperature water chiller is based on mechanical compression refrigeration, the precision water cooling device took the precise regulation of electric heating with controlled silicon by DC inverter compressor as temperature control device. In the paper, the reliability of the unit under the most unfavorable conditions was tested, the stability under different supplied water temperature was analysed. The experimental results showed that the process of reaching two-way regulating method of temperature control and effective stability and stability is 0.03 ℃.The semiconductor chiller cooled the hot end of the semiconductor by high stability (±0.1 ℃) of the cooling water, at the same time, the performance analysis under different working conditions and semiconductor system temperature stability and capacity of resisting disturbance under different working conditions of the semiconductor system were tested and analysed. The experimental results showed that, the COP is 0.73 under the nominal operating conditions, when the semiconductor heat dissipating end cooling water was 20 ℃, and the supply water temperature was increased to 16℃from 12 ℃, the cop increased by 24%; while the supply water temperature was increased to 20 ℃ from 16 ℃, the cop increased by 9.0%. Under the condition of the water supply temperature of the semiconductor was 20℃, when the cooling water temperature was reduced from 30℃ to 25℃,the semiconductor COP is increased by 5%; when the cooling water temperature was reduced from 25 ℃ to 20℃, the semiconductor COP is increased by 10%. When the supply water temperature the increase of the terminal load increased the temperature fluctuation of the supplied water, but all effective controlled in the range of±0.01℃. When the semiconductor systems were subject to 1.5kW,2kW transient thermal shock load, the response time of the system were respectively 100s and 120s and balance stability temperature is±0.01 ℃.The two sets of systems were tested in the case of external interference, to offset the interference with the cooling capacity and the electric heating, so as to maintain the temperature stability of energy regulation. When the precision constant temperature water chiller provided stable degree of ±0.03 ℃ cooling water to cool the semiconductor hot end, the temperature stability of the supplied water of the semiconductor chiller is ±0.005℃.The combination of the improved traditional compression refrigeration and semiconductor refrigeration, fully solve the traditional control system of high precision temperature control precision is not high enough and instability, provides a new solution for precision temperature control environment.