Engineering Answers

Steam at a temperature of 623 K is flowing through a pipe with an outer diameter of 100 mm. The pipe is insulated with 20-mm thick mineral wool, the average thermal conductivity of which is 0.055 W/m.K. Determine the outside surface temperature of mineral wool if the ambient air temperature is 300 K. Assume the hot-surface temperature of the mineral wool is the same as that of the flowing steam and the value of the surface coefficient of the insulating material is 30 W/m².K.

combustion of methane with air . the volumetric analysis of the products oon a dry basis revela sthe following

If 45 m3 of combustion products at 1000 K of the following

composition: 6.2 % O2, 1.0% H2O, 12.3 % CO2, and the balance N2 are cooled at atmospheric pressure from 1000 K to 250 K, what is

the enthalpy change in the J?

Calculate the enthalpy change that occurs when 5 lb of CO2 change

state from 8 psia and a mixture containing 20 % liquid plus solid to

200 oF by a constant volume process.

A 15 MW steam-driven turbine operates in the steady-state using 30

kg/s of steam. The inlet condition for the steam is p = 3000 kPa and

450 oC. The outlet condition is 500 kPa, saturated vapor. The

entering velocity of the steam is 250 m/s and the exiting velocity is

40 m/s. What is the transfer in kW for the turbine as the system?

What fraction is the heat transfer of the power generated?

A system composed of 2 kg of the above fluid expands in a frictionless piston and cylinder machine from an initial state of 1 MPa, 100°C to a final temperature of 30 degrees * C . If there is no heat transfer, find the net work for the process.

The % live bacteria due to sterilization follows an exponential relation such as % live = 30 exp (-0.01 T). T is the temperature in oC. What should be the temperature to achieve just less than 5% live bacteria?

The percentage of microorganisms remaining vs. exposure time to autoclave sterilization process follows % = 70-t*2. The percentage of microorganisms remaining vs. exposure time to dry heat sterilization process follows % = 80-t*5. At what time both the methods are equally efficient?

If the densities are 7.9 and 4.0 gm/cc, what is the average density?

15 mm dia SS (Young’s modulus = 200 Gpa) rod is coated with HA (Young’s modulus = 300 Gpa). What should be the coating thickness (in mm) so that the Young’s modulus of the composite is 209 Gpa (use mixture rule)?