5.

Water reaches the wellhead of a single flash geothermal plant at 2.0 MPa, 210°C, and 22.5 kg/s. The water is flashed to 800 kPa. The vapor portion goes through a turbine with an isentropic efficiency of 90% and the condenser pressure is 10 kPa. Both pumps have efficiencies of 68% and the injection well pressure is 4.0 MPa. Determine: a. The power produced by the turbine, in kW b. The total pump power input, in kW. c. The rate of heat input in the earth or "boiler," in kW d. The overall efficiency

3. The electronic components of a computer consume 0.1 kW of electrical power. To prevent overheating, cooling air is supplied by a 25 W fan mounted at the inlet of the electronics enclosure. At steady state, air enters the fan at 20°C, 1 bar and exits the electronics enclosure at 35°C. There is no significant energy transfer by heat from the outer surface of the enclosure to the surroundings and the effects of kinetic and potential energy can be ignored. Determine the volumetric flow rate of the entering air, in m³/s.

5. 5.15 To increase the thermal efficiency of a reversible power cycle operating between reservoirs at TH and Tc, would you increase TH while keeping Tc constant, or decrease Tc while keeping TH constant? Are there any natural limits on the in- crease in thermal efficiency that might be achieved by such means?

4. Valves on steam lines are commonly encountered and you should know how they work. For most valves, the change in velocity of the fluid flow is negligible. Apply this principle to solve the following problems. a. A pressure gage on a high-pressure steam line reads 80 bar absolute. A small quantity of steam is bled out through a valve to atmospheric pressure at 1 bar. A thermocouple placed in the bleed stream reads 400°C. What is the temperature inside the high-pressure line? b. Steam traps are common process devices used on the lowest points of steam lines to remove condensate. By using a steam trap, a chemical process can be supplied with so-called "dry" steam, i.e. steam free of condensate. As condensate forms due to heat losses in the supply piping, the liquid runs downward to the trap. As liquid accumulates in the steam trap, it causes a float mechanism to move. The float mechanisms is attached to a valve, and when the float reaches a control level, the valve opens to release accumulated liquid, then closes automatically as the float returns to the control levels. Most steam traps are constructed in such a way that the inlet of the steam trap valve is always covered with saturated liquid when opened or closed. Consider such a steam trap on a 7 bar(absolute) line that vents to 1 bar (absolute). What is the quality of the stream that exits the steam trap at 1 bar?

8. Water is pumped from one storage tank to a higher tank at a steady rate of 1L/s. The difference in the elevations of the two water tanks is 50 m. The storage tank, which serves a source, is open to the atmosphere, while the tank receiving the water has a pressure of 170.3 kPa. The length of the suction piping is 10 m and the length of the discharge piping is 75 m. The power supplied by an electric motor to the pump shaft is 1000 W. All piping is 1-in, schedule-40 steel pipe. Find the pump efficiency.

6. 7. An orifice having a diameter of 1" is used to measure the flowrate of a fluid (S.G. =0.85, viscosity=20 cp) in a horizontal, 2-in, sch 40 pipe at 70 F. The pressure drop is measured by a mercury monometer (SG=13.6), which read 3.0 cm. Calculate the volumetric flowrate of the fluid. An underground pressurized water tank is used to fill an elevated tank at 100 gpm of water. process. The underground tank is 20 feet below the pump with is used to transfer the liquid to the elevated tank 50 feet above the pump and open to the atmosphere. The pump is 10 hP, n=0.9, with a NPSHR of 30 feet. The suction side piping is 35 feet, 3" Schedule-40 carbon steel, the discharge piping is 65 feet, 2" schedule-40 carbon steel. Friction loss through fitting and valves may be disregarded. What is the minimum pressure in Tank 1 that will allow the pump to work without cavitation? 20 2 50 ft

1. 2. 3. 4. 5. 6. Describe the basic components and operation of a screw pump. Describe the basic components of a lobe pump. List the typical startup and shutdown procedures for a positive displacement pump. List the typical startup and shutdown procedures for a centrifugal pump. Describe how to startup a dynamic compressor. Describe how to startup a positive displacement compressor?

7. What is the equivalent length of the following pipe (200 ft, 2"-sch 40) and fitting and connections? Gate Valve Wide Open 90⁰ Swing Check Valve 45° Globe Valve Half Open 90⁰

2. A solar collector panel with a surface area of 32 ft² receives energy from the sun at a rate of 150 BTU/hr per ft² of collector surface. Thirty-six percent of the incoming energy is lost to the surroundings. The remainder is used to heat liquid water from 110 to 140°F. The water passes through the solar collector with a negligible pressure drop. Neglecting kinetic and potential energy effects, determine (at steady state) the mass flow rate of water, in lb/min. How many gallons of water at 140°F can eight collectors provide in a 30 minutes?

Using the 6 steps discussed in class, complete the following problem: A pump draws water through a piping arrangement at a mass flow rate of 20 lb/s. At the pipe inlet, the pressure is 14.7 psi, the temperature is 68F, and the water flows at a speed of 10 ft/s. At the pipe exit, the temperature is 68F, the pressure is 20 psi, and the velocity is 40 ft/s. Determine the power required by the pump in hp and Btu/s if the exit is 50 ft above the inlet.