FLOW BOILING HEAT TRANSFER AND TWO-PHASE PRESSURE DROP OF R134A IN A MICROFINNED HELICALLY COILED TUBE

2005 ◽  
Vol 19 (01n03) ◽  
pp. 581-583
Author(s):  
W. Z. CUI ◽  
L. J. LI ◽  
Q. H. CHEN ◽  
M. D. XIN
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Boiling ◽  
Transfer Enhancement ◽  
Two Phase ◽  
Coiled Tube ◽  
Frictional Pressure Drop ◽  
Helically Coiled Tube ◽  
Flow Boiling Heat Transfer ◽  
Evaporative Heat Transfer

The performance of evaporator is of importance in cryogenic and refrigeration systems. In this paper, evaporative heat transfer and pressure drop characteristics of refrigerant R134a boiling inside a new geometry microfinned helically coiled tube is experimentally studied. Compared with corresponding smooth helically coiled tube, the heat transfer enhancement factors of microfinned helically coiled tube are up to 2.2 with the varieties of mass flux and heat flux. The frictional pressure drop values are obtained by subtracting acceleration pressure drop and gravitational pressure drop from the measured total pressure drop. The frictional pressure drop data can be well correlated using Lockhart–Martinelli method.

Convective Boiling Heat Transfer and Pressure Drop Characteristics of R134a in a Microfinned Helically Coiled Tube

2005 ◽  
Author(s):  
Wenzhi Cui ◽  
Longjian Li ◽  
Mingdao Xin ◽  
Qinghua Chen ◽  
Quan Liao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Mass Flux ◽  
Boiling Heat Transfer ◽  
Annular Flow ◽  
Convective Boiling ◽  
Coiled Tube ◽  
Frictional Pressure Drop ◽  
Helically Coiled Tube

The main purpose of this paper was to experimentally study the heat transfer and pressure drop characteristics of refrigerant R134a boiling inside a new geometry microfin helically coiled tube. Experiments were performed in a range of mass quality from 0.05 up to 0.9, mass velocity 70 ∼ 380 kg/m2s and heat flux 2.0 ∼ 21.8 kW/m2. The local and average convective boiling heat transfer coefficients were reported in this paper, which were found to be dependent on both of mass flux and heat flux. Compared with corresponding smooth helically coiled tube, the microfin helically coiled tube could enhance the convective boiling heat transfer very well. The enhancement factor was up to 2.2 with the variety of mass flux and heat flux. Heat transfer in annular flow was specially studied. A flow boiling heat transfer correlation was presented for the annular flow regime, which had a mean deviation of 9.1%. The frictional pressure drop values were obtained by subtracting acceleration pressure drop and gravitational pressure drop from the measured total pressure drop. The frictional pressure drop data can be well correlated by Lockhart-Martinelli parameter. Considering the corresponding flow regimes, i.e., stratified and annular flow, two frictional pressure drop correlations were proposed, and showed a good agreement with the respective experimental data.

Flow Boiling Heat Transfer of R134a in a Vertical Helically Coiled Tube

2018 ◽  
Vol 40 (16) ◽  
pp. 1393-1402
Author(s):  
Xiaojuan Niu ◽  
Huaijie Yuan ◽  
Chen Quan ◽  
Bofeng Bai ◽  
Liang Zhao
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Coiled Tube ◽  
Helically Coiled Tube ◽  
Flow Boiling Heat Transfer
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