Fundamental process and system design issues in CO2 vapor compression systems

Experimental evaluation of the energy efficiency of a CO2 refrigerating plant working in transcritical conditions

“…Operation and efficiency of transcritical carbon dioxide refrigerating systems are highly influenced by pressure and refrigerant temperature at the gas-cooler outlet [8,19], these variables being independent in the supercritical region and, therefore, the test campaign was designed in accordance with the independence of these variables. The experimental tests were performed for fixed gas-cooler refrigerant outlet temperatures operating at fixed evaporating temperatures while varying the gas-cooler pressure.…”

“…Within carbon dioxide technical advantages, it could be highlighted its high heat transfer coefficients in the supercritical region [8] and its high pressure levels combined with low specific volumes, which allow the size of the components to be reduced. On the side of disadvantages, carbon dioxide needs special equipment due to the high working pressures, and a special regulation it is required because temperature and pressure are decoupled in the supercritical working region and a maximum efficiency is presented [8,9].…”

“…On the side of disadvantages, carbon dioxide needs special equipment due to the high working pressures, and a special regulation it is required because temperature and pressure are decoupled in the supercritical working region and a maximum efficiency is presented [8,9].…”

83. New Trends in the Field of Automobile Air Conditioning

“…CO 2 refrigeration system functions in air conditioning equipments right at the critical pressure of 7.38 MPa, or sometimes above it (Kim et al 2004). Heat transfer therefore takes place in many cases at supercritical temperatures and the cycle is transcritical, i.e., it has a subcritical low-pressure side and a supercritical high-pressure side.…”

“…An example of microchannel configurations for the internal heat exchanger is given in Fig. 6 (Kim et al 2004).…”