Comments on heat exchanger temperatures

[naupigos_gr]

hi

what kind of comments i could make on this excel spreadsheet about the heat exchangers?

[daiquiri]

It looks to me like you'd like someone else to pass the university exam for you...

[naupigos_gr]

haha yea of course
how the hell would i know something to comment if you don't teach me with a real piece of machinery prof !!!

regards

[naupigos_gr]

anyway i wrote the following..

"Parallel flow heat exchanger has an advantage when the two fluids need to be bought in the same temperature. Meaning that parallel flow heat exchanger is more efficient in transferring heat from hot fluid to cold fluid. On the other hand, counter flow heat exchanger design has three main advantages. First one, regarding the uniform temperature difference between the two fluids which results in minimization of thermal stresses throughout the exchanger. Secondly, the outlet temperature of the hot fluid is able to approach the highest temperature of hot fluid. Lastly, the uniform temperature difference produces a uniform rate of heat transfer throughout the heat exchanger"

any comment on that?

[SheetWise]

Originally Posted by naupigos_gr

anyway i wrote the following..

"Parallel flow heat exchanger has an advantage when the two fluids need to be bought in the same temperature.

Advantage over what?
Does it really matter where I buy them?

Meaning that parallel flow heat exchanger is more efficient in transferring heat from hot fluid to cold fluid.

As opposed to transferring heat from cold to hot?

On the other hand, counter flow heat exchanger design has three main advantages.

Over what?

First one, regarding the uniform temperature difference between the two fluids which results in minimization of thermal stresses throughout the exchanger.

How do you transfer heat if the two liquids have uniform temperature?

Secondly, the outlet temperature of the hot fluid is able to approach the highest temperature of hot fluid.

If the output of the hot approaches the highest temperature of the hot, it must not be an efficient heat exchanger -- unless it's true that the two liquids have uniform temperature. But if that's true ... how do you rate efficiency?

Lastly, the uniform temperature difference produces a uniform rate of heat transfer throughout the heat exchanger.

Uniform temperature difference between what? I thought they were uniform.

[philSweet]

perhaps some comment on the size/weight (ie cost) of the heater exchanger needed to to the job for each case?

[naupigos_gr]

thanks your your reply SheetWise and philSweet.

i will have a look again and review my conclusions!!!


thks and best regards,

john