NUMERICAL SIMULATION AND STRUCTURE OPTIMIZATION RESEARCH ON HEAT TRANSFER CHARACTERISTIC OF CALCINER COOLING WATER JACKET

2018 ◽  
Author(s):  
Zitian Wu ◽  
Kunqing Song ◽  
Ming Gao
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Transfer Characteristic ◽  
Cooling Water ◽  
Structure Optimization ◽  
Transfer Characteristic ◽  
Water Jacket

NUMERICAL SIMULATION OF FLOW AND HEAT TRANSFER CHARACTERISTIC OF 4K REGENERATORS AT HIGH FREQUENCY

2012 ◽  
Vol 19 ◽  
pp. 406-416
Author(s):  
ZHUOPEI LI ◽  
YANLONG JIANG ◽  
ZHIHUA GAN ◽  
LIMIN QIU
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
High Frequency ◽  
Heat Transfer Characteristic ◽  
Pressure Ratio ◽  
Transfer Characteristic ◽  
Ideal Gas ◽  
Maximum Pressure ◽  
Pulse Tube ◽  
Flow And Heat Transfer

Regenerator is a key component for all regenerative cryocoolers. 4K regenerative cryocoolers can be applied to provide cooling for low temperature superconductors, space and military infrared detectors, and medical examination etc. Stirling type pulse tube cryocoolers (SPTC), one type of regenerative cryocoolers, operate at high frequencies. As a result, SPTCs have the advantage of compact structure and low weight compared with G-M type pulse tube cryocoolers operating at low frequencies. However, as the frequency increase the thermal penetration depth of helium gas in the regenerator is greatly reduced which makes the heat transfer between the gas and the regenerator worse. In order to improve the heat transfer efficiency, regenerator materials with smaller hydraulic diameters are used. Therefore the flow resistance between the gas and the regenerator material will increase leading to larger pressure drop from the hot end to the cold end of the regenerator. The cooling performance is deteriorated due to the decreased pressure ratio (maximum pressure divided by minimum pressure) at the cold end. Also, behavior of helium at 4K deviates remarkably from that of ideal gas which has a significant influence both the flow and heat transfer characteristic within a regenerator. In this paper numerical simulation on the behavior of a 4K regenerator at high frequency is carried out to provide guidance for the optimization of the flow and heat transfer performance within a regenerator. Thermodynamic analysis of effect of the non-ideal gas behavior of helium at 4K on 4K regenerator at high frequency is investigated.

Condensation of R134a Flowing Inside Horizontal and Vertical Helicoidal Pipe

1999 ◽  
Author(s):  
H. J. Kang ◽  
C. X. Lin ◽  
M. A. Ebadian
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Water Flow ◽  
Heat Transfer Characteristic ◽  
Cooling Water ◽  
Transfer Characteristic ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Mass Fluxes ◽  
Flow Reynolds Number

Abstract Condensing heat transfer characteristic of an ozone-friendly refrigerant HFC-R134a (Hydrofluorocarbon R134a) flowing inside a 12.7mm helicoidal tube was investigated experimentally to obtain heat transfer data and correlations. For this long helicoidal pipe at horizontal and vertical helicoidal positions, heat transfer measurements were performed for the refrigerant flow mass fluxes from 100 to 400 kg/m2/s, in the cooling water flow Reynolds number range of 1500 < Rew < 9000 at fixed system temperature (33°C) and cooling tube wall temperature (12°C and 22°C). Experimental results show that, with the increase of mass flux, the overall condensing heat transfer coefficients of R134a increase. However, with the increase of mass flux (or the cooling water flow Reynolds number), the refrigerant side heat transfer coefficients decrease. The effects of cooling wall temperature on heat transfer coefficients were considered. Predictive correlations valid over the above water flow Reynolds number ranges and refrigerant flow mass fluxes were proposed. Helicoidal pipe heat transfer characteristics were compared with data from literature reports for horizontal straight tube. Experimental results show that helicoidal pipe, especially at horizontal position, conducts a much better heat transfer characteristic than that of horizontal tube even it was grooved. The helicoidal pipe’s position plays a very great role on heat transfer characteristic with 100 percent higher results at a horizontal position than that of vertical position.

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