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The SEER rating of a unit is the cooling output during a typical cooling-season divided by the total electric energy input during the same period. The higher the unit's SEER rating the more energy efficient it is. In the U.S., the SEER is the ratio of cooling in British thermal units (BTUs) to the energy consumed in watt-hours.
In the United Kingdom, a Seasonal Energy Efficiency ratio (SEER) for refrigeration and air conditioning products, similar to the ESEER but with different load profile weighting factors, is used for part of the Building Regulations Part L calculations within the Simplified Building Energy Model (SBEM) software, and are used in the production of Energy Performance Certificates (EPC) for new ...
The conversion factor is 3.41 BTU/hr/watt. Since a heat pump moves three to five times more heat energy than the electric energy it consumes, the total energy output is much greater than the electrical input. This results in net thermal efficiencies greater than 300% as compared to radiant electric heat being 100% efficient.
Higher COPs equate to higher efficiency, lower energy (power) consumption and thus lower operating costs. The COP usually exceeds 1, especially in heat pumps, because instead of just converting work to heat (which, if 100% efficient, would be a COP of 1), it pumps additional heat from a heat source to where the heat is required.
The same device used between the same temperatures is more efficient when considered as a heat pump than when considered as a refrigerator since C O P h e a t i n g = C O P c o o l i n g + 1 {\displaystyle \mathrm {COP} _{\mathrm {heating} }=\mathrm {COP} _{\mathrm {cooling} }+1}
The COP of absorption chillers can be improved by adding a second or third stage. Double and triple effect chillers are significantly more efficient than single effect chillers, and can surpass a COP of 1. They require higher pressure and higher temperature steam, but this is still a relatively small 10 pounds of steam per hour per ton of cooling.
Note that a Carnot engine is the most efficient heat engine possible, but not the most efficient device for creating work. Fuel cells, for instance, can theoretically reach much higher efficiencies than a Carnot engine; their energy source is not thermal energy and so their exergy efficiency does not compare them to a Carnot engine. [1] [2]
Superheated steam was widely used in main line steam locomotives. Saturated steam has three main disadvantages in a steam engine: it contains small droplets of water which have to be periodically drained from the cylinders; being precisely at the boiling point of water for the boiler pressure in use, it inevitably condenses to some extent in the steam pipes and cylinders outside the boiler ...