Alternative Heat Transfer Fluids Research Articles

Methodology for Comparison of Hydraulic and Thermal Performance of Alternative Heat Transfer Fluids in Complex Systems

A general method for the comparison of hydraulic and thermal performance of different liquid coolants in complex systems is offered. As a case study, the performance of polyalphaolefin (PAO) and a silicate ester-based fluid (Coolanol 25R) used as liquid coolants in avionic systems is presented. Thermophysical property expressions for the variation of density, specific heat, thermal conductivity, and kinematic viscosity with temperature for PAO and Coolanol 25R were developed. The range of temperature for this study was from — 54 to 135°C. Based on the results, the hydraulic performance of Coolanol 25R is much better than that of PAO at low temperatures (below 0°C) and in the laminar flow regime. In the turbulent region, PAO outperforms Coolanol 25R hydraulically over the entire temperature range. The thermal performance of PAO at temperatures below 6PC and in the laminar flow region is slightly better than that of Coolanol 25R: In the low-temperature turbulent region, Coolanol 25R outperforms PAO thernial...