PDF Publication Title:
Text from PDF Page: 006
HPWH Performance Report 1.4 Impact on Peak Demand The peak power of the Sanden units measured at 1.2 kW in the coldest weather, while the Rheem unit consumed 5.5 kW of peak power when both the heat pump and electric element operate simultaneously. Considering that most of the water heaters replaced had a rated power of 3 to 4.5 kW , this poses the question of whether there is a demand penalty associated with the new Rheem units with larger elements. To explore this, we looked at the average power consumption of all ducted units over the 36 coldest days4 from the 2017-2018 heating season to better understand the coincidence between water heater use and system peak. As shown in in Figure 4, the Sanden units show their highest hourly average demand of 300-watts at 2 am, well before the morning peak window and another smaller 180-watt demand from 7 to 9 pm. The peak Rheem demand does line up with the evening peak demand reaching 750 watts at 7 pm. Part of this difference is explained by differing water draw patterns (Rheem participants drew almost double the amount of water in the evenings than the Sanden participants5) across a limited sample size (7 Sanden units and 4 ducted Rheem units). However, the results suggest the following: ➢ Sanden units display a more even demand profile as they run more hours throughout the day and have no backup electric element that causes a demand spike during high water draws. ➢ Even on the coldest days, the time the electric element comes on for one Rheem unit does not always coincide with other units and when it does some of the units operate in heat pump mode. The result is an average peak demand across all units that is significantly less than the 5.5 kW instantaneous power. ➢ Even if the backup electric element in a new water heater is larger, this should not exacerbate the system peak depending on coincidence, because increased element will result in shorter runtimes. ➢ The stored energy in hot water tanks is an excellent DR resource, which can allow the hot water heater to be interrupted for several hours without the loss of delivered hot water. Figure 4: Average Demand Profile During the 36 Coldest 2017-2018 Days6 4 Weather taken from the Victoria University weather station. Actual weather varied across the sites at three different climate zones, but should align well with the peak demand windows. The 36 coldest days during the performance period averaged 3.5°C and saw temperatures as low as -2.4°C. The Kelowna sites saw temperatures as low as -17.6°C and the Rossland sites saw a minimum temperature of -15.7°C. 5 Sanden sites peaked at 21.7 litres/hour average at 7pm; Rheem sites peaked at 11.9 liters/hour at 7pm 6 Figure 4 shows average hourly power for all Sanden and Rheem units excluding the unducted Rheem unit. 4PDF Image | CO2 Integrated Heat Pump Water Heater
PDF Search Title:
CO2 Integrated Heat Pump Water HeaterOriginal File Name Searched:
CO2-Integrated-Heat-Pump-perf.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 | RSS | AMP |