Change of state

2009-03-16 12:55 am

Shrimp dumplings are cooked by condensing steam on them.One such cooker supplies steam at 110C at the rate of 0.1kgmin^-1.
(Given c(steam)=2000Jkg^-1C^-1,c(water)=4200Jkg^-1C^-1,Iv(water)=2.26x10^6Jkg^-1)

Thx

回答 (1)

天同

2009-03-16 5:44 am

✔ 最佳答案

You have not specified exactly what your question is. If you are asked to find the heat supplied to the dumplings in 1 minute, the calculation will be as follows:
Assume a time interval of 1 minute,
heat given by by steam in lowering the temperature from 110 C to 100 C = 0.1 x 2000 x (110-100) J = 2000 J
Heat given out by steam on condensing
= 0.1 x 2.26x10^6 J = 226 000 J
Assume the dumplings are at a temperature of T degrees C, then heat given out by water to fall from 100 C to T
= 0.1 x 4200 x (100-T) J
Hence, total heat given out = 2000 + 226000 +420(100-T) J

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