Heat Transfer problem

2010-09-18 9:59 pm

Consider a drinking glass full of ice water (liquid water and lots of ice cubes) that is at a temperature of 32 F (0 C). The surrounding air is still and no wind, the air temperature is 80 F, and the dew point temperature is 65 F. (a) Describe two processes, other than radition, that will act to add energy (or heat) to the ice water through the sides of the glass (do not need to discuss energy or heat exchange through the top and bottom of the glass of ice water). (b) Even though heat is being added, you notice that the temperature of the ice water inside the glass remians steady 32 . Explain.

回答 (1)

天同

2010-09-19 11:57 pm

✔ 最佳答案

(a) (i) Conduction of heat from the outside air to the ice water because of the temperature difference between the two.

(ii) The air surrounding the glass is cooled down to below dew point, water droplets will then be formed and adhered on the side of the glass. The latent heat of evapouration produced during condensation will then be absorbed by the ice water.

(b) The added heat will provide the necessary latent heat to melt the ice cubes. Before all ice cubes are melted, there will not be any rise of temperature as the ice cubes are staying at temperature of 32 F (melting point of ice) throughout.

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