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Heat transfer enhancement in cryogenic quenching process
J N Chung1, S R Darr1, Jun Dong1
1Cryogenics Heat Transfer Laboratory, Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, 32611-6300, U.S.A.
International Journal of Thermal Sciences = Revue Generale De Thermique
|September 11, 2020
Summary
Coating metal tubes with low thermal conductivity layers significantly improves cryogenic quenching heat transfer efficiency. This enhancement can reduce cryogen consumption by up to 53%.
Area of Science:
- Materials Science
- Heat Transfer Engineering
- Cryogenics
Background:
- Cryogenic quenching is crucial for material processing.
- Optimizing heat transfer in cryogenic processes is essential for efficiency.
- Current methods face challenges in maximizing cooling rates and minimizing cryogen usage.
Purpose of the Study:
- To investigate the impact of low thermal conductivity coatings on metal tubes for enhanced cryogenic quenching.
- To quantify the improvement in heat transfer efficiency using coated tubes.
- To determine the effect of coating thickness and liquid nitrogen flow rate on quenching performance.
Main Methods:
- Experimental evaluation of heat transfer in metal tubes with varying low thermal conductivity coating thicknesses.
- Utilizing liquid nitrogen as the coolant at different mass flow rates.
- Measuring quenching efficiency and cryogen consumption.
Main Results:
- Inner surface coating of tubes significantly enhanced quenching efficiency.
- Quenching efficiency increased with more coating layers and decreased mass flow rates.
- Observed efficiencies ranged from 40.6% to 80%.
- Percentage increase in efficiency ranged from 4.2% to 109.1% compared to bare surfaces.
Conclusions:
- Low thermal conductivity coatings are effective in improving cryogenic quenching heat transfer.
- Optimized coating and flow conditions can lead to substantial efficiency gains.
- Coated tubes offer potential for significant reductions in cryogen consumption, up to 53%.
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