Analysis of a Tube-in-Tube Heat Exchanger for a Space 4K Hybrid JT Cryocooler

Transcription

1 Analysis of a Tube-in-Tube Heat Exchanger for a Space 4K Hybrid JT Cryocooler Yuexue Ma, Jia Quan, Juan Wang, Jianguo Li, Yanjie Liu, Jingtao Liang Key Laboratory of Space Energy Conversion Technologies, Technical Institute of Physics and Chemistry CAS, Beijing, China ABSTRACT INTRODUCTION Cryogenics and its applications in space have made a remarkable amount of progresses over to improve their sensitivity and reduce the background noise, so miniaturization of 4 K cryocool mechanical cryocoolers working at 4 K, that have been launched or are under development are 4 He JT cooler precooled by an adsorption cryocooler 1 for JT coolers JT refrigerator due to its good heat transfer performance, compact structure, low cost and simple manufacture process 7-9 Cryocoolers 20, edited by S.D. Miller, R.G. Ross, Jr. and J.R. Raab International Cryocooler Conference, Inc., Boulder, CO,

2 272 REGENERATOR & RECUPERATOR INVESTIGATIONS COUNTER-FLOW HEAT EXCHANGER The Hybrid JT Cooler eters of the inner tube are d i and d o oi Figure 1. Schematic of the hybrid JT cooler

3 TUBE-IN-TUBE HEAT EXCHANGER FOR SPACE 4K HYBRID JT 273 Analysis Method Figure 2. Schematic of tube-in-tube heat exchanger R tubev parameters on heat transfer is carried out by comparing condition1 and condition2 when parameters such as d i, d o, and d oi Gz Nu l cr Gz f de Nu t cr c t f l where Gz=Re*Pr*d e /L, c r Nu l Nu t d e Q h Ql qm hin hout where Tm A is the heat transfer area based on the outside surface area of the inner tube, q m h in and h out Table 1. Different sizes of tubes d i d o d oi case1 case2 case4 case6

4 274 REGENERATOR & RECUPERATOR INVESTIGATIONS Figure 3. Heat transfer coefficient of Hex1 at different cases 10 K Re d D where is correction resistance, f e RESULTS AND DISCUSSION d oi is inner and outer diameter of the inner tube increases are illustrated d i and d o the outer side can be enhanced as d o at condition1 with case1 at condition2 whose cross section area of the high pressure side and low overall s more, its velocity result, the pressure drop of condition2 is lower than condition1 which is preferred

5 TUBE-IN-TUBE HEAT EXCHANGER FOR SPACE 4K HYBRID JT 275 Figure 4. Heat transfer coefficient of Hex2 at different cases or b d i d i is discussed with decreasing d i d i is shown in Table d i d io d oi d i d io d oi condition1 condition2 condition1 condition2 Table 2. Heat transfer and pressure drop of Hex1 h i1 2 h o1 2 K 1 2 i1 o1 h i1 2 h o1 2 K 1 2 i1 o1 Table 3. Heat transfer and pressure drop of Hex2 h i2 2 h o2 2 K 2 2 i2 o2 h i2 2 h o2 2 K 2 2 i2 o2

6 276 REGENERATOR & RECUPERATOR INVESTIGATIONS Table 4. Pressure drop of Hex3 condition1 condition2 i o i o Figure 5. Heat transfer coefficient and pressure drop of Hex2 at different d i DISCUSSION Based on all the discussion above, it is obvious that the heat transfer characteristics of the tubes and the arrangement of the Better heat transfer performance can be achieved by on the premise of ensuring that the pressure drop is in CONCLUSIONS ACKNOWLEDGMENT

7 TUBE-IN-TUBE HEAT EXCHANGER FOR SPACE 4K HYBRID JT 277 REFERENCES Cryocoolers 10,. Cryogenics, 2010, 9 space telescope SPICA Cryogenics, ( telescope SPICA Cryogenics, cryocoolerscryogenics, 46, 2 Science China Technological Sciences, Chemical engineering research and design International Journal of Thermal Sciences Computers & chemical engineering 10 Chemical Engineering Science