Question

Problem 5.078 Ground source heat pumps operate by using the soll, rather than amblent air, as the heat source (or sink) for heating (or cooling) a bulding. A liquid transfers energy from (to) the sol by way of bur ed plastic tubing. The tubing is at a depth for which annual variations in the temperature of the soil are much less than those af the ambient air. For example, at a locatian suth as Sauth Bend, Indiana, deep-ground temperatures may remain at approximately 11°C, while annual excursions in the ambient air temperature may range fram -21°C to 37°C. Consider the tuhing to be laid aut in a dlasely spaced serpentine arrangement. Ta what depth shoud the tubing be buried so that the sail can be viewed as an infinite mediu at canstant tempereture aver a 12- monen period? Account forthe oerodic cooling 《heating》 or the soil due to boon annual changes in ambient conditions and variations in heat pump Operation rrom the winter heating to tne summer cooing mode. Soil surface ump Buried tubing Heat pumpBuried tubing Top view The tubing should be burled m deep.

Answer 1

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