5 Cheb Group2
- 1. Group 2 LACABA, Severo NAVARRO, Jo-anne PARAS, Lota TAMSE, Aldrin
- 2. 2. Determine the optimum economic thickness of insulation that should be used under the following conditions: saturated steam is being passed continuously in a horizontal 1” Sch 40 steel pipe. The temperature of the steam is valued at $0.0035/kg. the pipe is to be insulated with a material that has a thermal conductivity of 0.06W/mK. The cost of the installed insulation per m of pipe length is $200x, where x is the thickness of the insulation in meters. Annual fixed charges including maintenance amount to 20% of the initial installed cost. The total length of the pipe is 250 m, and the average temperature of the surroundings is 27degC. Heat transfer coefficient at the outside of the insulation may be assumed constant for all insulation thickness.
- 3. GIVEN: Saturated steam Horizontal 1” Sch 40 steel pipe
- 4. WORKING EQUATIONS: EQUATION FOR CHECKING:
- 6. A condenser for a distillation unit must be designed to condensed 200 kg/h of vapor. The effective condensation temperature for the vapor is 180ºC. The heat of condensation for the vapor is 450000J/kg. Cooling water is available at 25ºC. The cost of cooling water is $22/1000m 3 . The optimum Heat Transfer Coefficient is 300 W/m 2 K. The cost of the installed heat exchanger is $400/m 2 and annual fixed charges including maintenance are 20% of the initial investment. The heat capacity of the water is 4184 J/kgK. If the condenser is to operate 7200 hrs/yr, determine the cooling water flow rate in kg/hr and exit temperature for the optimum economic conditions.
- 7. Given: t steam =180ºC + 273 = 453K t 1 = 25ºC + 273 = 298K U = 300 W/m 2 K Hy = 7200 hrs/yr Cw = $22/1000m 3 Cp = 4184 J/kgK Ca = $400/m 2 K F = 0.2 L steam = 450000 J/kg W steam = 2000 kg/hr Solution:
- 9. An air cooler consisting of a bundle of 2” Sch 40 steel pipes enclosed in a well baffled shell is being built to cool 200 kg/hr of air from 80 o C to 28 o C. The air flows under pressure through the tubes of a 1-shell 2-tube pass heat exchanger. Cooling water at 20 o C is under sufficient pressure to force it through at any desired rate, flows through the shell. The heat transfer coefficient based on the inside fluid is 48 W/m 2 K and for the outside fluid, 2000 W/m 2 K. Cooling water costs PhP 0.57/m 3 and the annual fixed charges is 22% with cooler cost at PhP 24,000/m 2 . Calculate the Optimum exit temperature of cooling water and optimum length of tubes.