Question

Please explain every thing and show me even your small detail >> thank you (its very important to me)

Saturated air at 40 F is first preheated and then saturated adiabatically. This saturated air is then heated to a final condition of 105F and 28% RH. To what temperature must initially be heated in the preheat coil? (use Psychrometry chart & Show all detail statements in your answer.) Find a) Show the processes on the psychrometric chart. b) To what temperature must initially be heated in the preheat coil?

Answer 1

Initial Final condition: T=40F conditiew: It = 105F RH281. constant enthalpy T line constant specific humidity line 228%. RH - TOSF 40F constant relatine humidity dire The temperature marked abone is the temperature to which air must be preheated in the preneat coil. T= 102F Approx.

So, here in order to solve this we go backwards from final condition to initial condition.

Finally, the temperature is 105F and 28% RH and just before that it was saturated air. So, if no vapour are added to it then it would follow constant specific humidity line. So, it goes backwards from point 4 to point 3.

Before the process of 3-4, it is given that the air is saturated adiabatically. That means, the process will follow constant enthalpy line. So, it starts coming down from point 3. Now, we have to find point 2.

Considering the initial condition, it is given that the air is at 40F and saturated so, we have found the point 1. Now, the air is heated that means no vapour addition so, it will follow constant humidity line. Now, the intersection of this line( along the constant humidity line) and the line coming down from point 3 (along constant enthalpy) line will give the point 2. The air is heated to this temperature at point 2.

Temperature at point 2 is coming out to be approximately 102F.