Shell and Tube Evaporator

[haniyah]

Dear all,

Its the first time that i am designing the shell and tube type evaporator and for this i have made an excel sheet for ease of calculations but i am not sure and content whether i have done right or wrong and for this i have attached my calculation sheet for you to check and comment if i am wrong any where. My design is based on the following information:

Refrigerant = R404
Capacity = 145 kW
Liquid = 23% concentrated sodium chloride solution
Liquid in= -9 deg. Centigrade
Liquid out = -10 deg. centigrade
flow = 141 cubic meter per hour
evaporating temp = -13 deg centigrade
condensing temp = 30 deg centigrade

I request this forum to check my sheet and comment as early as possible as i have to give my design to manufacturing deptt.

Thanks in advance.

My attachments includes: Extract of book from where i picked the calculation procedure, Ashrae chapter 30 for thermo physical properties of refrigerants and my excel sheet.

 

[haniyah]

extract of book is attached here

 

[srfish]

Hi,

As an oldtimer I am used to dealing in British units. In these units specific heat = 1.041 and thermal conductivity = .102. These look about right for 23% NaCl solution. If I use your value for viscosity of 2.3 it calculates to a much highr Prandl number of 56.8 instead of 5.24.

For the tubeside flow I used a conversion factor of 7936.6 to convert the 33.2 Kg/s to 263,508 lb/hr. This will give a much higher value than the given tube velocity.

Did I make the conversions correct?

 

[haniyah]

Thanks for your reply srfish. Plz check other things too and tell me whether i have taken right values for R-404 at given condensing and evaporating temperature?????

I request other members too to take part in this......

 

[srfish]

Hi,

In using a conversion factor of 3412.1 for the heat exchanged, I get 494,755 Btu/hr for the overall heat exchanged and 682,784 Btu for the tube side heat exchanged for R-404A. The shell side would not check because of the high flow that was mentioned before.