CO2 for cooling
CO2 for cooling
(OP)
Does anyone have any thoughts pro/con on using CO2 for cooling?
Here's a link:
http:// www.troxai tcs.com/ai tcs/news/n ews/0206_c o2_mcc.php
thanks
Here's a link:
http://
thanks
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RE: CO2 for cooling
CO2 at higher evaporating temps involves some pretty high pressures; (45 deg. F. and Satn is around 600 Psia) and direct to ambient condensing results in a transcritical system: rejected heat is all sensible heat, none of the advantages of Phase Change available. This last condition leads to low COP's on systems condensing over 88 deg.F.; and the equipment for 88 deg. F. would have to withstand about 1300 Psig to achieve "normal" conformity to codes, etc.
Sanyo has designed a suitable compound compression circuit for lower capacities and transcriticalapplications; it inherently supports a gas displacement overcirculation arrangement. Other players include Linde, Nestle, and Star Refrigeration in the UK.
By comparison with R-717, major driving forces for design with CO2 include: Smaller Vessels, compressors and piping; easier tranportation for oil and liquid in an overfeed arrangement; and lack of toxicity should a leak or discharge develop. There is an inclination with "compact" CO2 circuits to simply leave out a number of the valves that would nominally be on an industrial system, simply because the easiest way to manage charge during servicing is to dump it and renew it.
RE: CO2 for cooling
http://
The chiller system appears to be designed around standard air conditioning parameters. The primary refrigeration system: R134a chiller supplying 43degF CHW absorbs about 10degF worth of heat from the secondary refrigerant-CO2. The secondary CO2 refrigerant system is self contained except for the interconnecting piping. One drawback as you mention is the high operating pressures ie. 50bar or 735psi. I suspect this turns the project into a hybrid type of HVAC piping project with the additon of process piping (hi pressure welded SS tubing) not to mention additional costs.