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which gives COPLZ = T2s −T3 (T2s−T3)−T0⋅ln⎜ 2s⎟ 3 – Theoretical Background and System Analysis With reference to the definition of the COP of the reversed Carnot cycle (Gosney, 1982), the COP of the modified Lorentz cycle is defined as: COPLZ = Tm and Tm =T2s −T3 T−T ⎛T⎞ (3.1) (3.2) m 0 ln⎜ 2s ⎟ ⎝ T3 ⎠ where the subscripts 2s and 3 refer to the inlet and outlet temperature of the heated fluid (heat sink), T0 is the temperature of the heat source and Tm is the thermodynamic average temperature during heat rejection. Whereas the Carnot efficiency is often used as a measure for the thermo- dynamic efficiency of conventional heat pump cycles, the Lorentz effi- ciency can be used for the transcritical CO2 cycle. The Lorentz efficiency is defined as (Klöcker, 1998): ηLZ = COPHP (3.3) COPLZ where the subscript HP refers to the real CO2 heat pump cycle. Table 3.1 shows, as an example, the measured COP of residential CO2 heat pumps for low-temperature space heating (Kerherve and Clodic, 2002) and hot water heating (Saikawa and Hashimoto, 2000) as well as the calculated Lorentz COP (COPLZ) and the Lorentz efficiency (ηLZ) for the systems. Table 3.1 clearly demonstrates that the thermodynamic losses in a CO2 heat pump water heater are considerably smaller than in a CO2 heat pump system for low-temperature space heating. The 25% higher Lorentz effi- ciency of the heat pump water heater is caused by the better temperature fit between the high-pressure CO2 and the water in the counter-flow gas cooler (ref. Appendix A2.4, Optimum High-Side Pressure when Incorpo- rating Real Gas Cooler Performance). ⎛T⎞ ⎝ T3 ⎠ 27PDF Image | Residential CO2 Heat Pump System for Combined
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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
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