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COPc = h1−h3 h2−h1 COPh =h2−h3 h2−h1 On the air side, assuming constant specific heat and neglecting latent heat transfer: Qsystem = m&air ⋅cp,air ⋅∆Tair (3.3) (3.4) (3.5) where, ∆Tair is the temperature difference between the return and supply air. For a given cycle and specified capacity the required refrigerant mass flow can be determined from the equations above. The air-side mass flow rate for a given air inlet and exit temperature difference, or the air-side exit temperature difference for a given air mass flow rate and inlet temperature can also be calculated. 3.2 Ideal heat pump cycle In a vapor compression cycle, minimizing the source/sink temperature and pressure difference maximizes cycle efficiency. In the subcritical cycle, because heat is rejected at a constant temperature, the condensing temperature can theoretically match the indoor air temperature. However, comfort considerations limit the extent to which the condensing temperature can be reduced. To provide a given capacity requirement at lower condensing temperature the airflow rate must be increased. The result is one of the primary drawbacks of heat pumps, that the higher flow rate of delivered air at a lower temperature results in a “drafty” environment in the conditioned space. Increasing the discharge pressure from the compressor can increase the supply air temperature, but a penalty is paid in cycle efficiency. 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 -400 -300 T=33 C T=30 C T=40 C T=21 C Figure 3.2 R744 pressure enthalpy diagram -200 -100 -0 Enthalpy (kJ/kg) The R744 cycle must operate near the critical point in order to deliver supply air at temperatures warmer than the human body. Under certain conditions an increase in pressure results in greater cycle capacity than the 13 Pressure (kPa)PDF Image | Comparison of R744 and R410A
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CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
Heat Pumps CO2 ORC Heat Pump System Platform More Info
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