Supercritical CO2 conjugate heat transfer and flow analysis in a rectangular microchannel subject to uniformly heated substrate wall

2020 ◽  
Vol 19 ◽  
pp. 100596 ◽  
Author(s):  
Javad Khalesi ◽  
Nenad Sarunac ◽  
Zahra Razzaghpanah
Keyword(s):  
Heat Transfer ◽  
Supercritical Co2 ◽  
Conjugate Heat Transfer ◽  
Flow Analysis ◽  
Rectangular Microchannel ◽  
Heated Substrate

A Numerical Study on Conjugate Heat Transfer for Supercritical CO2 Turbine Blade With Cooling Channels

2020 ◽  
Author(s):  
Akshay Khadse ◽  
Andres Curbelo ◽  
Ladislav Vesely ◽  
Jayanta S. Kapat
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Supercritical Co2 ◽  
Conjugate Heat Transfer ◽  
Maximum Temperature ◽  
Inlet Temperature ◽  
Cooling Channels ◽  
Blade Cooling ◽  
Turbine Inlet

Abstract The first stage of turbine in a Brayton cycle faces the maximum temperature in the cycle. This maximum temperature may exceed creep temperature limit or even melting temperature of the blade material. Therefore, it becomes an absolute necessity to implement blade cooling to prevent them from structural damage. Turbine inlet temperatures for oxy-combustion supercritical CO2 (sCO2) are promised to reach blade material limit in near future foreseeing need of turbine blade cooling. Properties of sCO2 and the cycle parameters can make Reynolds number external to blade and external heat transfer coefficient to be significantly higher than those typically experience in regular gas turbines. This necessitates evaluation and rethinking of the internal cooling techniques to be adopted. The purpose of this paper is to investigate conjugate heat transfer effects within a first stage vane cascade of a sCO2 turbine. This study can help understand cooling requirements which include mass flow rate of leakage coolant sCO2 and geometry of cooling channels. Estimations can also be made if the cooling channels alone are enough for blade cooling or there is need for more cooling techniques such as film cooling, impingement cooling and trailing edge cooling. The conjugate heat transfer and aerodynamic analysis of a turbine cascade is carried out using STAR CCM+. The turbine inlet temperature of 1350K and 1775 K is considered for the study considering future potential needs. Thermo-physical properties of this mixture are given as input to the code in form of tables using REFPROP database. The blade material considered is Inconel 718.

Numerical Investigation on Conjugate Heat Transfer of Supercritical CO2 in a Horizontal Double-Pipe Heat Exchanger

2017 ◽  
Author(s):  
Zhenxing Zhao ◽  
Jun Wu ◽  
Yuansheng Lin ◽  
Qi Xiao ◽  
Fan Bai ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Supercritical Fluid ◽  
Supercritical Co2 ◽  
Conjugate Heat Transfer ◽  
High Mass ◽  
Heat Transfer Deterioration ◽  
Flow And Heat Transfer ◽  
Double Pipe ◽  
Pipe Heat

The special fluid flow and heat transfer characteristics of supercritical CO2 in a horizontal double-pipe heat exchanger have been numerically investigated. The AKN k-epsilon model was selected to model the turbulent flow and heat transfer of supercritical fluid. In conjugate heat transfer process, there exists obvious heat transfer deterioration on the top wall for horizontal flow. The region of heat transfer deterioration expands with the increased GShell or TShell,0, and the influence of TShell,0 on conjugate heat transfer is greater than that of GShell. The high-temperature fluid will gather near the top region. The intensity and position of the secondary flow can represent the turbulence heat transfer. When the supercritical fluid temperature is much higher than Tpc, buoyancy force can be omitted, but it can not been neglected even under relatively high mass flux.

Flow Prediction and Conjugate Heat-Transfer Analysis of a Counter Flow Heat-Exchanger with Protruded Fin

2020 ◽  
Vol 12 (3) ◽  
Author(s):  
Manikandan Mohan ◽  
K.C. Udaiyakumar
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Conjugate Heat Transfer ◽  
Flow Analysis ◽  
Heat Transfer Analysis ◽  
Counter Flow ◽  
Tube Heat Exchanger ◽  
Flow Heat ◽  
Optimized Model ◽  
Cfd Method

Voluminous cram has been carried out in this project which is intended to improve the conjugate heat-transfer performance of a heat-exchanger. In this study, CFD method is effectively used to predict the effect of Protruded Fins in heat exchanger, which protrudes inside the tube in addition to the shell side. CFD analysis on Protruded Finned Heat Exchanger (PFHE) is carried out with three different fin configurations like rectangular, triangular and parabolic fins. The baseline model of counter flow shell-tube heat-exchanger is considered with standard dimensions and analyzed initially without fins. Later the numbers of fins are increased to optimize the fin position and counts. The shape of the fins is then modified to find an optimized model with a higher heat-transfer coefficient. Hence, the present conjugate heat-transfer and flow analysis focus on optimizing the number of fins for a heat-exchanger with counter flow along with the shape optimization of fins. The computational values are measured with the net heat exchange between the cold and hot-fluids in terms of temperature difference. Also, the area averaged surface heat transfer co-efficient (h) of the heat exchanger with different fin configurations are plotted and compared.

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