Carbon dioxide flow boiling in a single microchannel – Part II: Heat transfer

2011 ◽  
Vol 35 (4) ◽  
pp. 597-611 ◽  
Author(s):  
Maxime Ducoulombier ◽  
Stéphane Colasson ◽  
Jocelyn Bonjour ◽  
Philippe Haberschill
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Flow Boiling

Study on Flow Boiling Heat Transfer of Carbon Dioxide With PAG-Type Lubricating Oil in Pre-Dryout Region Inside Horizontal Tube

2010 ◽  
Author(s):  
Chaobin Dang ◽  
Minxia Li ◽  
Eiji Hihara
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Flow Boiling Heat Transfer ◽  
The Heat Transfer Coefficient

In this study, the boiling heat transfer coefficients of carbon dioxide with a PAG-type lubricating oil entrained from 0 to 5 wt% in a horizontally placed smooth tube with an inner diameter of 2 mm were experimentally investigated under the following operating conditions: mass fluxes from 170 to 320 kg/m2s, heat fluxes from 4.5 to 36 kW/m2, and a saturation temperature of 15 °C. The results show that for a low oil concentration of approximately 0.5% to 1%, no further deterioration of the heat transfer coefficient was observed at higher oil concentrations in spite of a significant decrement of the heat transfer coefficient compared to that under an oil-free condition. The heat flux still had a positive influence on the heat transfer coefficient in low quality regions. However, no obvious influence was observed in high quality regions, which implies that nucleate boiling dominates in the low quality region whereas it is suppressed in the high quality regions. Unlike the mass flux under an oil-free condition, mass flux has a significant influence on the heat transfer coefficient, with a maximum increase of 50% in the heat transfer. On the basis of our experimental measurements of the flow boiling heat transfer of carbon dioxide under wide experimental conditions, a flow boiling heat transfer model for horizontal tubes has been proposed for a mixture of CO2 and polyalkylene glycol (PAG oil) in the pre-dryout region, with consideration of the thermodynamic properties of the mixture. The surface tension and viscosity of the mixture were particularly taken into account. New factors were introduced into the correlation to reflect the suppressive effects of the mass flux and the oil on both the nucleate boiling. It is shown that the calculated results can depict the influence of the mass flux and the heat flux on both nucleate boiling and convection boiling.

TWO-PHASE FLOW BOILING AND CONDENSATION HEAT TRANSFER CHARACTERISTICS OF NATURAL REFRIGERANTS: REVIEW

2013 ◽  
Vol 21 (04) ◽  
pp. 1330003 ◽  
Author(s):  
JAEHYEOK HEO ◽  
HOSEONG LEE ◽  
RIN YUN
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Flow Boiling ◽  
Environmentally Friendly ◽  
Condensation Heat Transfer ◽  
Environmental Concerns ◽  
Phase Flow ◽  
Heat Transfer Characteristics ◽  
Two Phase ◽  
Transfer Characteristics

The existing artificial and chemical refrigerants have been phased out due to environmental concerns, and they have been replaced with environmentally friendly refrigerants. Among them, carbon dioxide, ammonia, and hydrocarbons are paid attention as next generation refrigerants, and their application has been widely expanded. Therefore, in this paper, the latest studies of flow boiling and condensation heat transfer characteristics of carbon dioxide, ammonia, and hydrocarbon are reviewed. The heat transfer characteristics of ammonia and hydrocarbon show the relatively similar trends with the conventional refrigerants compared to those of carbon dioxide. The general trends and recommendable models of flow boiling and condensation heat transfer with carbon dioxide, ammonia, and hydrocarbons are summarized.

Sign in / Sign up

Export Citation Format

Share Document