Chapter 7, Problem 7.47P

1. As shown in the following figure, a diffuser has one inlet (i) and one outlet (e). Liquid water flows through the diffuser. The diffuser runs at a steady state. The pressure of the water is 3 bar. The temperature of the water is 300 K. The specific volume of water is 0.001 m³/kg. The mass flow rate at the inlet is mį = 1 kg/s. The cross area of the inlet is A; 10 cm². The cross area of the outlet is Ae 50 cm². Determine the following components: = = (i) The mass flow rate at the outlet me (ii) The volumetric flow rate at the inlet and outlet, (AV); and (AV)ė, respectively. (iii) The velocity of water flow at the inlet and outlet, V¡ and Vė, respectively. (iv) The specific enthalpy change of the control volume: h₂ — h₁. (v) Discuss the possible function of this diffuser. i e

The figure below shows a turbine-driven pump that provides water to a mixing chamber located dz = 5 m higher than the pump, where in = 50 kg/s. Steady-state operating data for the turbine and pump are labeled on the figure. Heat transfer from the water to its surroundings occurs at a rate of 2 kW. For the turbine, heat transfer with the surroundings and potential energy effects are negligible. Kinetic energy effects at all numbered states can be ignored. h2 = 417.69 kJ/kg Mixing chamber Ocy = 2 kW Steam P3 = 30 bar T3 = 400°C dz Turbine Pump P4 = 5 bar T4 = 180°C Saturated liquid water m, Pi = 1 bar Determine: (a) the magnitude of the pump power, in kW. (b) the mass flow rate of steam, in kg/s, that flows through the turbine.

Two separate streams of air and steam flow through a compressor system and a heat exchanger, as shown in the figure. The diagram provides steady state operating data for this system. The transfer of heat with the surroundings can be neglected, as well as the effects of kinetic and potential energy. Air can be considered an ideal gas. Decide:a) The total power generated by both compressors:            kW b) The mass flow of water:        kg/s

Assume 5.08 lb/sec of fluid enter a steady- state, steady-flow system with P1 = 97.71 psia, p1 = 0.309 lb/ft, v1 = 94.19 fps, u1 = 793.23 BTU/lb, and leave with P, = 15.54 %3D %3D %3! %3D %3D psia, p2 = 0.148 Ib/ft°, v2 = 470.44 fps, and u2 = 772.14 BTU/lb. During the passage %3D %3D through the open system, each pound rejects 12.4 BTU of heat. Determine the work in hp.

Current Attempt in Progress A pump is used to circulate hot water in a home heating system. Water enters the well-insulated pump operating at steady state at a rate of 0.42 gal/min. The inlet pressure and temperature are 14.7 Ibf/in.?, and 180°F, respectively; at the exit the pressure is 90 Ibf/in.2 The pump requires 1/25 hp of power input. Water can be modeled as an incompressible substance with constant density of 60.58 Ib/ft and constant specific heat of 1 Btu/lb · °R. Neglecting kinetic and potential energy effects, determine the temperature change, in °R, as the water flows through the pump. AT = i °R

The figure below provides steady-state data for a throttling valve in series with a heat exchanger. Saturated liquid Refrigerant 134a enters the valve at a pressure of 9 bar and is throttled to a pressure of p2 = 2 bar. The refrigerant then enters the heat exchanger, exiting at a temperature of 10°C with no significant decrease in pressure. In a separate stream, liquid water at 1 bar enters the heat exchanger at a temperature of 25°C with a mass flow rate of m˙4= 4 kg/s and exits at 1 bar as liquid at a temperature of 15°C. Stray heat transfer and kinetic and potential energy effects can be ignored.   Determine:(a) the temperature, in °C, of the refrigerant at the exit of the valve.(b) the mass flow rate of the refrigerant, in kg/s.

The figure below provides steady-state data for a throttling valve in series with a heat exchanger. Saturated liquid Refrigerant 134a enters the valve at a pressure of 9 bar and is throttled to a pressure of p2 = 1 bar. The refrigerant then enters the heat exchanger, exiting at a temperature of 10°C with no significant decrease in pressure. In a separate stream, liquid water at 1 bar enters the heat exchanger at a temperature of 25°C with a mass flow rate of m4 = 4 kg/s and exits at 1 bar as liquid at a temperature of 15°C. Stray heat transfer and kinetic and potential energy effects can be ignored. -Heat exchanger 1 2 3 wwww P3 = P2 T3 = 10°C Saturated liquid R-134a at p, = 9 bar Valve P2 5 T5 = 15°C P5 = P4 Water T = 25°C P4 = 1 bar Determine: (a) the temperature, in °C, of the refrigerant at the exit of the valve. (b) the mass flow rate of the refrigerant, in kg/s.

The figure belows shows three components of an air-conditioning system, where T3 = 115°F and ng = 3 lb/s. Refrigerant 134a flows through a throttling valve and a heat exchanger while air flows through a fan and the same heat exchanger. Data for steady-state operation are given on the figure. There is no significant heat transfer between any of the components and the surroundings. Kinetic and potential energy effects are negligible. Air T = 535°R p= 0.240 Btu/lb-"R Saturated liquid R-134a T3, m3 Fan Wey=-0.2 hp Throttling valve 5 www Saturated vapor Ps=P4 P.= 60 lbfin.? T;= 528°R +2 - Heat exchanger Modeling air as an ideal gas with constant c, = 0.240 Btu/lb - °R, determine the mass flow rate of the air, in Ib/s. mi = Ib/s

4.30 Refrigerant 134a enters a heat exchanger operating ai steady state as a superheated vapour at 10 bars. 60°C. where it is cooled and condensed to saturated liquid at 10 bars. The mass flow rate of the refrigerant is 10 kg/min. A separate stream of air enters the heat exchanger at 37°C with a mass flow rate of 80 kg/min. Ignoring heat transfer from the outside of the heat exchanger and neglecting kinetic and potential energy effects, determine the exit air temperature, in °C.