Chapter 5, Problem 5.12P

As a mechanical engineering technician, you are asked by your building manager to investigate the performance of a steam turbine at the main university building. Critically compare how heat transfer efficiency will affect the lifetime of the turbine.

An exhaust stream exits a plant at 1 atm and 160˚C at a rate of 1 m3/hr. Unfortunately, it includes 60,000 ppm of heptane, which was used as a solvent. Not only will this heptane contribute to ozone formation upon release, but this solvent costs $1.80 / L. The lost solvent, which has a specific gravity of 0.7, must be replaced when it exits in the exhaust. Consider proposing a cost-benefit analysis to the plant manager. One solution is to cool the exhaust stream, which requires energy and equipment. To recover 35% of the heptane before it is released to the atmosphere, what temperature would the exhaust need to be before exiting? How much money could the proposed equipment and operation cost per day while still breaking even?

Crude oil, Cp = 1.9 kJ/(kg.K), flows at a rate of 0.32 kg/s through the inner pipe of a tube-in-tube heat exchanger and it is heated from 29 °C to 96 °C. Another hydrocarbon, Cp = 2.50 kJ/(kg. K), enters at 240 °C. The overall coefficient of heat transfer is found to be 4200 W/(m?K). Determine for a minimum temperature difference of 20 °C between the hot and cold Nuids; a) the LMTD for parallel flow and for counterflow heat exchamger; b) the surface area for both heat exchanger configurations; c) mass Now rate of hot Nuid for both heat exchanger configurations.

A jet condenser discharge water at 37°C with inlet cooling water at 8°C, condenser pressure is 0.01 MPa. Calculate the kg of condensing water per kg of exhaust steam with a quality of 88%. Steam and water properties:h2 = 2297.49 KJ/kg, h at 0.01 MPa and 88% qualityh1 = 33.06 KJ/kg, hf at 8°Ch3 = 155 KJ/kg hf at 37°C

Steam generators are a type of heat exchanges that are used in power plants to generate steam at desired pressure and temperature (Fig. Q1.b). In a steam generator, saturated liquid water at 30°C enters a 60-mm diameter tube at the volume flow rate of 12 L/s. After exchanging heat with hot gas, the water changes to steam and leaves the generator at a pressure of 9 MPa and a temperature of 400°C. During this process, the diameter of the water/steam tube does not change.(i) Calculate the steam mass flow rate.

Steam generators are a type of heat exchanges that are used in power plants to generate steam at desired pressure and temperature (Fig. Q1.b). In a steam generator, saturated liquid water at 30°C enters a 60-mm diameter tube at the volume flow rate of 12 L/s. After exchanging heat with hot gas, the water changes to steam and leaves the generator at a pressure of 9 MPa and a temperature of 400°C. During this process, the diameter of the water/steam tube does not change.(i) Calculate the steam mass flow rate.  (ii) What is the inlet velocity of the steam?  (iii) What is the exit velocity of the steam?

A 5-feet diameter Chimney is designed to handle a flue gas produced in a steam power plant at a rate of 17 lb/s. The barometric pressure is 29.92-inch Hg. Outside air enters the combustion chamber at 90 F. The average temperature of the flue gas inside the Chimney is 572 F and its molecular weight is 30. Cv = 0.35, Rair = 53.342 ft-lb/lb-R. Calculate: 5. The total draft, feet of air. 6. The height of the Chimney, feet

Steam generators are a type of heat exchanges that are used in power plants to generate steam at desired pressure and temperature (Fig. Q1.b). In a steam generator, saturated liquid water at 30°C enters a 60-mm diameter tube at the volume flow rate of 12 L/s. After exchanging heat with hot gas, the water changes to steam and leaves the generator at a pressure of 9 MPa and a temperature of 400°C. During this process, the diameter of the water/steam tube does not change.(ii) What is the inlet velocity of the steam?

Water enters a uniformly heated vertical tube of diameter 2.5 cm and length 4.5 m. Total heat applied to the tube is 650 kW. Inlet pressure, temperature, and mass flow rate of water are given as 100 bar, 285 C, and 1.5 kg/s, respectively. Find the pre-heating length, exit quality, and various pressure differentials terms.