PDF Publication Title:
Text from PDF Page: 229
Space Heating Only (SH Mode) ♦ The highest COP, approx. 3.15, was measured at 33/28oC supply/- return temperatures for the SH system and 8 MPa high-side pressure. ♦ The COP dropped off by approximately 4 and 12% when the supply/return temperatures were increased from 33/28oC to 35/30oC and 40/35oC, respectively (i.e. ~1.8% per oC). All Modes ♦ The COP in the combined mode at 33/28oC supply temperature was approximately 5 to 10% higher than that of the DHW mode, and the higher the DHW temperature the larger the relative difference. At 35/30 and 40/35oC supply/return temperatures and 60 to 70oC DHW temperature, the COPs were virtually identical. ♦ The COP in the SH mode was 12 to 28% lower than that of the com- bined mode, and the lower the DHW temperature and the higher the temperature level in the SH system, the larger the relative difference. The experimental results clearly demonstrated, that for all operating modes a reduction in the temperature level(s) for the SH system and/or the DHW system would lead to a higher COP for the CO2 heat pump unit. During operation in the combined mode and DHW mode, it was observed that the lower the inlet water temperature to the DHW preheating gas cooler unit, the higher the COP. Hence, an integrated CO2 heat pump unit should preferably supply heat to a low-temperature space heating system (ref. Section 2.3, Hydronic Heat Distribution Systems), and the set-point temperature for the DHW system should not exceed the minimum national temperature requirement (ref. Section 2.4.2.3, Examples of System Designs). The highest COP will be achieved in regions having a relatively low city water temperature, and when the thermodynamic losses in the DHW tank due to conductive heat transfer and mixing of hot and cold water has been minimized by means of adequate measures (ref. Section 7.1.2.4). Since the supercritical CO2 rejects heat at a gliding temperature in a counter-flow tripartite gas cooler, it is mainly the return temperature in the SH system that affects the COP of the heat pump unit in the combined mode and the SH mode, and not the supply temperature. The reason is that the return temperature represents the theoretical minimum CO2 inlet temperature for the DHW preheating gas cooler unit, and the lower the temperature level, the larger the possible cool-down of the CO2 before throttling. 7 – Discussion and Analysis 207PDF Image | Residential CO2 Heat Pump System for Combined
PDF Search Title:
Residential CO2 Heat Pump System for CombinedOriginal File Name Searched:
20559406.pdfDIY PDF Search: Google It | Yahoo | Bing
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
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)