Chapter 5, Problem 5.30CU

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 shows a turbine-driven pump that provides water to a mixing chamber located dz = 25 m higher than the pump, where in = 20 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. h = 417.69 kJ/kg Mixing chamber Ocy = 2 kW Steam P3 = 30 bar T3 = 400°C dz Wev Turbine Pump P4 = 5 bar 4 T = 180°C Saturated liquid water m, PL = 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.

The figure below shows a turbine-driven pump that provides water to a mixing chamber located dz = 25 m higher than the pump, where in = 80 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. h = 417.69 kJ/kg Mixing chamber Oey = 2 kW Steam P3 = 30 bar T3= 400°C dz Turbine Pump P4 = 5 bar T= 180°C 14 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.

The figure below shows a turbine-driven pump that provides water to a mixing chamber located dz = 45 m higher than the pump, where n = 80 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. h = 417.69 kJ/kg Mixing chamber Ocy = 2 kW Steam P3 = 30 bar T; = 400°C dz Turt Pump P4 =5 bar -4 T = 180°C Saturated liquid water m, Pj = 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.

Assume 3.15 lb/sec of fluid enter a steady-state, steady-flow system with P1 = 92.43 psia, P1 = 0.392 lb/ft, v1 = 95.09 fps, u = 793.46 BTU/lb, and Jeave with P2 = 13.49 psia, p2 = 0.191 lb/ft, v2 = 499.53 fps, and u2 = 773.05 BTU/lb. During the passage through the open system, each pound rejects 11.1 BTU of heat. Determine the work in hp. %3D %3D !!

3. A hydraulic lift is shown below. The combined mass of the piston, rack, and car is 4000 lbm. The working fluid is water. There is no heat transfer to or from the water, and the internal energy of the water per unit mass is constant. The water may be considered incompressible. (a) Taking all the water in the reservoir, line, and hydraulic cylinder as the system (i.e., taking the closed-system approach), calculate the work necessary to raise the rack and car 1 ft (neglect the change in potential energy of the water in the system). (b) Repeat part (a), taking all the water plus the car and the rack as the system. (c) Repeat part (a), taking an open-system approach; choose as your system the volume of the hydraulic cylinder, excluding the piston, rack, and car. If the absolute pressure in the system is 1000 lbf/in², calculate the volume that must flow in to raise the car 1 ft. Reservoir Pump Hydraulic cylinder

4.105 Separate streams of steam and air flow through the tur- bine and heat exchanger arrangement shown in Fig. P4.105. Steady-state operating data are provided on the figure. Heat transfer with the surroundings can be neglected, as can all kinetic and potential energy effects. Determine (a) T3, in K, and (b) the power output of the second turbinc, in kW. W 10,000 kW W = Turbine Turbine P3 = 10 bar T3= ? T= 400°C P2= 10 bar T=240°C P4 =1 bar Steam in ww www 4. T = 600°C P= 20 bar Ts= 1500 K 5 Ps=1.35 bar m = 1500 kg/min +6 Heat exchanger VT= 1200 K P6=1 bar Air in Fig 4.105

Assume 1.62 lb/sec of fluid enter a steady-state, steady-flow system with P1 = 95.18 psia, ρ1 = 0.341 lb/ft3, v1 = 93.75 fps, u1 = 798.07 BTU/lb, and leave with P2 = 16.73 psia, ρ2 = 0.134 lb/ft3, v2 = 427.15 fps, and u2 = 761.09 BTU/lb. During the passage through the open system, each pound rejects 11 BTU of heat. Determine the work in hp.

Assume 2.30 lb/sec of fluid enter a steady-state, steady-flow system with P₁ = 105.73 psia, P1 = 0.324 lb/ft³, v₁ = 92.08 fps, u₁ = 792.25 BTU/lb, and leave with P2 24.04 psia, p2 = 0.113 lb/ft³, v₂ = 484.46 fps, and u₂ = 761.10 BTU/lb. During the passage through the open system, each pour rejects 11.7 BTU of heat. Determine the work in hp.