Srinivas S. Pitla

New correlation to predict the heat transfer coefficient during in-tube cooling of turbulent supercritical CO2

The Nusselt number variations of supercritical carbon dioxide during in-tube cooling are presented and discussed. Using data presented in this paper as well as prior publications, a new correlation to predict the heat transfer coefficient of supercritical carbon dioxide during in-tube cooling has been developed. The new correlation is presented in this paper. It is based on mean Nusselt numbers that are calculated using the thermophysical properties at the wall and the bulk temperatures, respectively. It is seen that the majority of the numerical and experimental values are within ±20% of the values predicted by the new correlation.

Heat Transfer from Supercritical Carbon Dioxide in Tube Flow: A Critical Review

Since the discovery that CFCs and HCFCs destroy the ozone layer and cause global warming, the need to regulate their use has been critical. In the ensuing research for new environmentally benign refrigerants, carbon dioxide has been considered due to its excellent thermophysical properties. This paper gives a review of the heat transfer and pressure drop characteristics of supercritical carbon dioxide in tube flow. This information is necessary for designing the gas cooler of a carbon dioxide refrigeration system. A comparison of the different heat transfer correlations applicable to cooling of supercritical carbon dioxide has also been made.

Convective Heat Transfer from In-Tube Cooling of Turbulent Supercritical Carbon Dioxide: Part 2—Experimental Data and Numerical Predictions

A combined experimental and numerical study of the heat transfer and pressure drop associated with in-tube cooling of supercritical carbon dioxide was conducted. The experimental measurements are presented and compared with numerical predictions obtained from the mathematical model presented in the first part of this two-part paper. Heat transfer and pressure drop data of practical utility for the design of a supercritical carbon dioxide gas cooler are also presented in this paper. The effects of the mass flow rate and pressure on the heat-transfer coefficient and the friction factor are examined and explained.

Convective Heat Transfer from In-Tube Flow of Turbulent Supercritical Carbon Dioxide: Part 1—Numerical Analysis

A mathematical model to simulate the turbulent flow of supercritical carbon dioxide during in-tube cooling is presented. The model is based on the Favre-averaged, parabolized Navier-Stokes equations and an appropriate turbulence model. Accurate thermophysical property data for supercritical carbon dioxide are used as input. The model is used to predict the variations of the heat transfer coefficient along the length of the tube. It is found that the heat transfer coefficient displays a maximum at some location downstream of the inlet. The model results are used to provide an explanation for the unusual behavior of the heat transfer coefficient and to gain insights on in-tube cooling of supercritical carbon dioxide.