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Control Technologies to Optimize Operating Performance of R744 Climate Control Systems
Published May 18, 2003 by Institution of Mechanical Engineers in United Kingdom
R744 ( CO2) is an environmental friendly natural refrigerant. Besides this aspect also the benefits of an R744 climate control system particularly the high cooling performance are now widely recognized.
It is shown that caused by the physical properties of R744, especially the low critical temperature, the development of appropriate control strategies are necessary, e.g., to avoid unacceptable high pressures after switch-on of the A/C system or at rapidly changing of speed (acceleration of the car).
On the other hand, the basic control concept is shown to optimize the efficiency of the system by controlling the high pressure in the supercritical operating range.
Basically the R744 A/C system is ready for series development. An SOP could be in the second half of the decade, depending on decisions of car manufacturers.