两种印刷电路板式微通道节流制冷器性能实验研究

Experimental study on performance of two types of printed circuit board microchannel J-T coolers

回热节流结构对微通道节流制冷器性能有决定性影响,针对目前微通道节流制冷器多为单层高、低压通道结构,制冷量较小的特点,结合印刷电路板工艺可刻蚀焊接形成不同结构的叠层通道、传热效率高的优点,设计制作出两种印刷电路板式微通道节流制冷器。两种制冷器交错的高低压通道各6层。第一种制冷器的通道结构为大小微槽道相搭配,实现先回热换热后节流,当量直径分别为463μm和120μm;第二种通道结构为错排微圆柱针肋,当量直径337μm,高低压板片均实现回热和节流并行发生。在2.02~5.20 MPa进口压力范围内实验研究两种制冷器性能,得到制冷器质量流量、进出口压力以及进出口和轴向测点的温度。结果表明,微槽道结构制冷器的节流段温降斜率明显大于回热段;微针肋结构前段温降斜率有略微增大的趋势,由于轴向导热和寄生热负荷的存在,后段温降趋缓。第一种制冷器在5.12 MPa进口压力下的质量流量为4.52 g/s,高压侧压降4.31MPa,最低温度为210.9 K,第二种制冷器在5.20 MPa入口压力下,质量流量为8.70 g/s,高压侧压降4.40 MPa,最低温度可达165.2 K。相比试件一先以回热为主再以节流为主的流程形式,试件二回热与节流同时作用,热力和传热过程有不同规律,具有明显更优的温降效果,是流量、压降、换热、热力过程相互影响的综合结果。随着微通道技术在气体节流领域的应用越来越多,换热过程中伴随显著节流效应越来越普遍,两试件对比实验研究可为今后此类问题的研究、设计与应用提供一些参考。

The regenerative throttling structure has a decisive influence on the performance of the micro-channel JT cooler.Considering the feature of low cooling capacity in micro channel J-T cooler,and the advantages of printed circuit board technology,such as multi layer,high heat transfer efficiency,etc.,two types of printed circuit micro channel J-T cooler are designed and manufactured.The J-T coolers have six interleaved high-pressure and lowpressure channels each.The channel structure of the first cooler is composed of large and small rectangle microchannels to realize heat exchange first and then throttling.The equivalent diameters are 463μm and 120μm,respectively.The channel structure of second cooler is staggered micro cylindrical pin ribs with an equivalent diameter of 337μm.Heat exchange and throttling are realized meanwhile in both the high and low pressure plates.The performance of the two coolers was experimentally investigated in the range of 2.02—5.20 MPa inlet pressure.The temperature at axial measuring points,mass flow rate and pressure drop are obtained.The results show that the temperature drop slope of the throttling section of the micro-channel structure refrigerator is significantly greater than that of the regenerative section;the temperature drop slope of the front section of the micro-needle rib structure has a slight increase trend.Due to the existence of axial heat conduction and parasitic heat load,the rear section temperature drop slows down.The tip temperature of first cooler is 210.9 K under 5.12 MPa when the mass flow rate is 4.52 g/s and pressure drop is 4.31 MPa;the second cooler can reach 165.2 K at 5.20 MPa when the mass flow rate is 8.70 g/s and pressure drop is 4.40 MPa.Compared with the order of heat exchange first and then throttling,heat exchange and throttling at the same tine have better temperature drop and different laws of heat transfer and thermodynamic process.It is the comprehensive result of the interaction of flow rate,pressure drop,heat transfer and thermal process.With the increasing application of microchannel technology in the field of gas throttling,heat transfer with throttling is more common,the comparative study of the coolers may provide some reference for such problems in the future.