Arne Jakobsen

A correlation of optimal heat rejection pressures in transcritical carbon dioxide cycles

Abstract In this work, a cycle simulation model has been developed to optimize the coefficient of performance (COP) of transcritical carbon dioxide air-conditioning cycles. The analysis shows that the COP of the transcritical carbon dioxide cycle varies nonmonotonically with the heat rejection pressure; a maximum COP occurs at an optimal heat rejection pressure. It is further revealed that the values of the optimal heat rejection pressure mainly depend on the outlet temperature of the gas cooler, the evaporation temperature, and the performance of the compressor. Based on the cycle simulations, correlations of the optimal heat rejection pressure in terms of appropriate parameters are obtained for specific conditions. The results are of significance for the design and control of the transcritical carbon dioxide air-conditioning and heat pump systems

Identification of Matrices in Science and Engineering

Engineering science is a scientific discipline that from the point of view of epistemology and the philosophy of science has been somewhat neglected. When engineering science was under philosophical scrutiny it often just involved the question of whether engineering is a spin-off of pure and applied science and their methods. We, however, hold that engineering is a science governed by its own epistemology, methodology and ontology. This point is systematically argued by comparing the different sciences with respect to a particular set of characterization criteria.