Theoretical Study on Cryogen Spray Cooling in Laser Treatment of Ota’s Nevus: Comparison and Optimization of R134a, R404A and R32

Jiameng Tian, Bin Chen, Zhifu Zhou and Dong Li
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Jiameng Tian: State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Bin Chen: State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Zhifu Zhou: State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Dong Li: State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China

Energies, 2020, vol. 13, issue 21, 1-20

Abstract: Cryogen spray cooling (CSC) could be applied clinically for the laser therapy of Ota’s nevus, a dermal hyperplastic pigmented disease with a morbidity rate of 0.1–0.6% in the Asian population. An accurate, efficient, complete simulation system that considers the entire spray cooling process, including cryogen flow in the tube nozzle, spray dynamics and internal phase change heat transfer (cold injury) in skin tissue, was established to determine suitable cryogen and cooling parameters. The optimum spray distances for R134a, R404A and R32 were determined to be 66.0, 43.1 and 22.5 mm, respectively. The corresponding maximum surface heat fluxes were 363.5, 459.9, and 603.6 kW?m −2 , respectively. The maximum surface heat flux of R32 with small spray distance was 1.66 times as large as that of R134a, indicating the potentially good cooling performance and precise targeted cooling of R32 during the laser therapy of Ota’s nevus. The cooling durations that caused cold injury of skin tissue were 2.3, 1.4, and 1.1 s for R134a, R404A, and R32, respectively. The interval between CSC and laser irradiation was optimized to 90–162 ms for R134a, R404A and R32, in consideration of the cooling effect, depth, uniformity, and risk of cold injury.

Keywords: cryogen spray cooling; nevus of Ota; laser therapy; cold injury; bio-heat transfer (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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