R-744 gas cooler model development and validation

Abstract

AJirst principles-based model was developed for a transcritical C02 gas cooler, using a finite element method. The model uses published correlations for refrigerant and airside heat transfer and pressure drop. Experimental results are presented at 48 operating conditions. The model predicted the gas cooler capacity within ±2% and pressure drop on the R744 side well within the range of experimental error. The model's usefulness is demonstrated by analyzing alternative circuiting and multi-slab designs.

Numerical Model for Microchannel Condensers and Gas Coolers With an Improved Air-Side Approach

“…As it can be observed, all the points deviate from the experimental data less than ±2 K. The predicted pressure losses of refrigerant were far from the experimental data, with a mean error of -80%. These errors are similar to those errors reported by Asinari et al (2004) and Yin et al (2001) when they evaluated this error with their own models for the same cases. Yin et al (2001) solve this disagreement introducing some dimensional changes in ports, produced by manufacturing defects.…”

“…Currently, several models or simulation tools for heat exchanger are available in the literature: for finned tubes (Lee and Domanski, 1997;Corberán et al, 2002;Jiang et al, 2006;Oliet et al, 2007b;Singh et al, 2008;CoilDesigner, 2010;EVAP-COND, 2010;IMST-ART, 2010;Oliet et al, 2010) and microchannel heat exchangers (Kim and Bullard, 2001;Yin et al, 2001;Asinari, 2004;Jiang et al, 2006;Oliet et al, 2007a;Shao et al, 2009;García-Cascales et al, 2010;MPower, 2010;Fronk and Garimella, 2011). Some of them (Kim and Bullard, 2001;Yin et al, 2001;Corberán et al, 2002;Asinari, 2004;Oliet et al, 2007a;Singh et al, 2008;Shao et al, 2009;CoilDesigner, 2010;IMST-ART, 2010;Oliet et al, 2010) apply energy conservation equations to each control volume, while others (Lee and Domanski, 1997;EVAP-COND, 2010;Jiang et al, 2006;Oliet et al, 2007b;García-Cascales et al, 2010;Fronk and Garimella, 2011) apply directly the solution given by the ε-NTU methodology.…”

“…Some of them (Kim and Bullard, 2001;Yin et al, 2001;Corberán et al, 2002;Asinari, 2004;Oliet et al, 2007a;Singh et al, 2008;Shao et al, 2009;CoilDesigner, 2010;IMST-ART, 2010;Oliet et al, 2010) apply energy conservation equations to each control volume, while others (Lee and Domanski, 1997;EVAP-COND, 2010;Jiang et al, 2006;Oliet et al, 2007b;García-Cascales et al, 2010;Fronk and Garimella, 2011) apply directly the solution given by the ε-NTU methodology. The main difference between both methodologies is that the ε-NTU model uses several implicit assumptions resulting in less freedom to describe the actual processes.…”

“…The experimental data used corresponds to a CO 2 gas cooler tested by Yin et al (2001), who measured the performance of the gas cooler over a wide range of operating conditions. The uncertainty for the capacity measurement in those experiments was ±5%.…”

Modeling supermarket refrigeration systems for supervisory control in smart grid

“…Most of the models developed for condenser need physical details like fin and tube dimensions [8], [9], [10] and thus are not directly applicable here since our modeling approach is mainly based on general knowledge about the system. So, neglecting condenser dynamics, the steady-state multi-zone moving boundary model developed in [3] is utilized here with further considerations.…”