3 ms·
> Cooling it down from 18C takes 5.6 kWh This seems like a lot. It's 20 megajoules, so even at a COP of 1, it's enough energy to cool down 20 megajoules / (41
by mlyle 4y ago
> Cooling it down from 18C takes 5.6 kWh
This seems like a lot. It's 20 megajoules, so even at a COP of 1, it's enough energy to cool down 20 megajoules / (4182 J/kg/K) / 18 K = 265 kilos of water by 18 kelvin.
And a refrigerator is supposed to attain a COP better than 1, and I suspect you have less thermal mass around than 265 kilos of water.
Something is wrong-- either in measurement, or heat exchangers very badly occluded by dust, etc, or some other fault.
- 8fingerlouie 4y agoIt does sound like a lot, and I’ve only measured once. The fridge is in a cabinet, enclosed on 3 sides, so maybe it’s not letting enough hot air out ? I could be wrong, but I think it was stated as using 184 kWh / year (at room temp 22C, optimal conditions), which is just over 0.5 kWh/day, and considering that the summerhouse is usually cooler than that (12-16C) when unoccupied, I would assume it used even less power. As it is, for this entire week, the heat pump has (self) reported using 1.8 kWh/day, and according to my power company, my daily consumption has been 1.8 kWh/day. Considering that there are 5-7 IoT things plugged in, the fridge probably isn’t using much power.
- mlyle 4y ago> The fridge is in a cabinet, enclosed on 3 sides, so maybe it’s not letting enough hot air out ? Seems likely. Once it succeeds in warming its cabinet, a big share of that heat leaks back into the fridge. (And efficiency falls because of the bigger temperature difference).