Open Access
ARTICLE
MODELING OF THE HEAT TRANSFER IN A SUPERCRITICAL CO2/DME MIXTURE FLOWING IN COOLED HELICALLY COILED TUBES
Yan Chena
, Qingxin Bab,*, Xuefang Lib
a School of Energy and Power Engineering, Shandong University, Jinan 250061, China
b Institute of Thermal Science and Technology, Shandong University, Jinan 250061, China
* Corresponding author. Email: qingxin90113@126.com
Frontiers in Heat and Mass Transfer 2021, 16, 1-9. https://doi.org/10.5098/hmt.16.18
Abstract
The heat transfer of supercritical CO
2/DME mixtures was modeled in this study for a mass ratio of 95/5 for cooling in horizontal helically coiled
tubes. The CO
2/DME heat transfer coefficient was higher in the high-temperature zone than with pure CO
2. The heat transfer of CO
2/DME (95/5)
was predicted for various mass fluxes, heat fluxes and pressures. The CO
2/DME heat transfer coefficient increased with the mass flux due to the
increased turbulent diffusion, and first increased but then decreased with the heat flux. The peak heat transfer coefficient of CO
2/DME shifted toward
the high-temperature region as the operating pressure increased. The effects of buoyancy and the centrifugal force were also analyzed to better
understand the heat transfer mechanisms in helically coiled tubes. The gravitational buoyancy effect on the heat transfer decreased with mass flux
while increased with heat flux. Higher heat fluxes strengthened the centrifugal buoyancy effect on the heat transfer at the beginning of the cooling
process but weakened the centrifugal buoyancy effect later in the cooling process. The present study gives insight into the flow and heat transfer
processes in helically coiled tubes which is useful for heat exchanger designs and refrigerant selection.
Keywords
Cite This Article
Chen, Y., Li, X. (2021). MODELING OF THE HEAT TRANSFER IN A SUPERCRITICAL CO
2/DME MIXTURE FLOWING IN COOLED HELICALLY COILED TUBES.
Frontiers in Heat and Mass Transfer, 16(1), 1–9.