Chapter 7, Problem 7.9CU

Q2/ In a reheat steam cycle, the maximum steam temperature is limited to 500 °C. The condenser pressure is 0.1 bar and the quality at turbine exhaust is 0.8778. Had there been no reheat the exhaust quality would have been 0.7592. Assuming ideal processes, determine (a) the reheat pressure, (b) the boiler pressure, (c) the cycle efficiency, and (d) the steam rate.

Steam enters the turbine of a vapor power plant at 600 lbf/in.2, 1300°F and exits as a two-phase liquid–vapor mixture at 90°F. Condensate exits the condenser at 85°F and is pumped to 600 lbf/in.2 The turbine and pump isentropic efficiencies are 90 and 80%, respectively. The net power developed is 1 MW.Determine:(a) the percent steam quality at the turbine exit.(b) the percent thermal efficiency.(c) the steam mass flow rate, in lb/h.

Steam enters the turbine of a vapor power plant at 600 lbf/in.2, 1000°F and exits as a two-phase liquid–vapor mixture at 90°F. Condensate exits the condenser at 85°F and is pumped to 600 lbf/in.2 The turbine and pump isentropic efficiencies are 90 and 80%, respectively. The net power developed is 1 MW.Determine:(a) the percent steam quality at the turbine exit.(b) the percent thermal efficiency.(c) the steam mass flow rate, in lb/h.

1. A. Using the Steam Tables, determine the amount of cooling water needed by a condenser in kg/sec if wet steam comes into the condenser at P= 610.44mmHG vac and 99.47 % moisture, mass flow rate= 7200+ (X/SN) kg/hr. Cooling water enters the condenser at 12 deg C and leaves at 21 deg C. Answer: B. Draw the schematic diagram of the condenser and process in the PV and TS diagrams below. Cp H20 = 4.187 KJ/(kg-K): Schematic diagram of heat exchanger =condenser S 2. Use only the MD below to solve this Item; use it by plotting data and process to determine items being asked. Steam enters a turbine at 117.4308 atmgage and 932 deg. F, and expands isentropicaly to 177.17 inches of Hg. For 2 + (X/SN) kg/sec of steam, what is (a) the ideal work done (KI/sec) if AKE = 0 and actual exhaust enthalpy is 2700 KI/kg. a)Ans: (b)ne =_ (c)Determine: (e) Actual steam temp ideal steam moisture at exhaust. Ans: at the exhaust. Ans. g) change in entropy during the actual process. Ans 3000 2500 2000…

-Gas supply line- Gas A 1.5 m3 tank initially contains a gas at 140 kPa, 340 K. The tank is connected a line carrying same gas at 1400 kPa and 340 K. What should be heat transfer during this process, in kJ, so that the final pressure and temperature are 1400 kPa and 340 K, respectively. (cp=0.72 kJ/kg.K, cv=0.48 kJ/kg.K).

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Which one is correct please ?

Refrigerant 22 enters the compressor of an air-conditioning unit operating at steady state at 40oF, 80 lbf/in.2 and is compressed to 140oF, 200 lbf/ in.2. The refrigerant exiting the compressor enters a condenser where energy transfer to air as a separate stream occurs and the refrigerant exits as a liquid at 200 lbf/in.2, 90oF. Air enters the condenser at 808F, 14.7 lbf/in.2 with a volumetric flow rate of 750 ft3/min and exits at 110oF. Neglecting stray heat transfer and kinetic and potential energy effects, and assuming ideal gas behavior for the air, determinea) The mass flow rate of refrigerant, in lb/min, andb) The compressor power, in horsepower.

Refrigerant 134a is the working fluid in a vapor compression heat pump that provides 35 kW heat to a dwelling. Saturated vapor enters the compressor at 1.6 bar, and saturated liquid exits the condenser, which operates at 8 bars. Isentropic efficiency of the compressor is 75%. The pressure drops across the condenser and evaporator can be neglected. Kinetic and potential energy changes are negligible. a) Determine the compressor power, in kW  b) Determine the coefficient of performance (COP)  c) Draw the processes in a T-s diagram