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Consider a carton of milk that is refrigerated at a temperature of
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Introduction to Heat Transfer
- Water is flowing in a 90ο pipe with uniform cross section area of A=0.0083 m2. The velocity along the horizontal direction is v1=6.0 m/s. The pressure at the section 1 is p1=500kPa. Elevation difference and energy losses can be neglected. The density of water is ρ=1000kg/m3. An external force is needed to hold the pipe in equilibrium. (1) Select the correct expression of the external force component in the horizontal direction Rx_________ A. B. C. D.arrow_forwardPressure cookers, in general, maintain a gage pressure of 2 atm (or 3 atm absolute) inside. Therefore, pressure cookers cook at a temperature of about 133°C instead of 100°C, cutting the cooking time by as much as 70 percent while minimizing the loss of nutrients. The newer pressure cookers use a spring valve with several pressure settings rather than a weight on the cover. A certain pressure cooker has a volume of 6 L and an operating pressure of 75 kPa gage. Initially, it contains 1 kg of water. Heat is supplied to the pressure cooker at a rate of 500 W for 30 min after the operating pressure is reached. Assuming an atmospheric pressure of 100 kPa, determine the temperature at which cooking takes place.arrow_forwardPressure cookers, in general, maintain a gage pressure of 2 atm (or 3 atm absolute) inside. Therefore, pressure cookers cook at a temperature of about 133°C instead of 100°C, cutting the cooking time by as much as 70 percent while minimizing the loss of nutrients. The newer pressure cookers use a spring valve with several pressure settings rather than a weight on the cover. A certain pressure cooker has a volume of 6 L and an operating pressure of 75 kPa gage. Initially, it contains 1 kg of water. Heat is supplied to the pressure cooker at a rate of 500 W for 30 min after the operating pressure is reached. Assuming an atmospheric pressure of 100 kPa, determine the amount of water left in the pressure cooker at the end of the process.arrow_forward
- Water is flowing in a 90ο pipe with uniform cross section area of A=0.0083 m2. The velocity along the horizontal direction is v1=6.0 m/s. The pressure at the section 1 is p1=500kPa. Elevation difference and energy losses can be neglected. The density of water is ρ=1000kg/m3. An external force is needed to hold the pipe in equilibrium. (2) Select the correct expression of the external force component in the vertical direction Ry_________ A. B. C. D.arrow_forwardA quantity of gas occupies a volume of 0.3m3 at a pressure of 100 MN/m2 and a temperature of 20oC. The gas is compressed isothermally to a pressure of 500 MN/m2and then expanded adiabatically to its initial volume. Determine for the quantity of gas :i. The heat received or rejected during the compressionii. The change of internal energy during expansion iii. The mass of the gaarrow_forwardWhile the electric current (i) passes through the circuit part in the figure, the power consumed in the resistor of R1=5Ω is 20 Watt. Accordingly, if it is immersed in 100 ml of distilled water at 22°C in an insulated glass with a resistance of R2=7Ω, after how many minutes will the temperature of the water rise to 25°C?arrow_forward
- The pump of a water distribution system is powered by a 15-kW electric motor whose efficiency is 90 percent. The water flow rate through the pump is 50 L/s. The diameters of the inlet and outlet pipes are the same, and the elevation difference across the pump is negligible. If the absolute pressures at the inlet and outlet of the pump are measured to be 100 kPa and 300 kPa, respectively, determine (a) the mechanical efficiency of the pump and (b) the temperature rise of water as it flows through the pump due to mechanical inefficiencies.arrow_forwardDetermine the amount of energy (kJ) that needs to be transferred to the water toraise its temperature to 160°F if a water heater is initially filled with 55 gallons ofwater at 50°F.arrow_forwardWhat are extensive and intensive properties? What is an isolated system? What is a quasi-static process? What is a manometer? What are the two types of manometers? What is a thermocouple? What is zeroth law of thermodynamics? What is a dimension? A unit? What is mechanical equilibrium? chemical equilibrium? thermal equilibrium? Electrical equilibrium? What is thermodynamic equilibrium? What is the seebeck effect? What is the instrument used to measure emf? At what temperature does glass begins to soften?arrow_forward
- An 80-percent-efficient pump with a power input of 20 hp is pumping water from a lake to a nearby pool at a rate of 1.5 ft3 /s through a constant-diameter pipe. The free surface of the pool is 80 ft above that of the lake. Determine the mechanical power used to overcome frictional effects in piping.arrow_forwardA 1.2 mm diameter tube is inserted into an unknown liquid whose density is 960 kg/m^3, and it is observed that the liquid rises 5 mm in the tube, making a contact angle of 15 degree. Determine the surface tension of the liquid. h = 5mm = 0.005m d = 12x10^-4m r = 6x10^-4m angle = 15 y = 960kg/m^3 = 9.414 kn/m^3arrow_forwardA hydraulic turbine is used to generate power by using the water in a dam. The elevation difference between the free surfaces upstream and downstream of the dam is 130 m. The water is supplied to the turbine at a rate of 150 kg/s. If the shaft power output from the turbine is 155 kW, the efficiency of the turbine is (a) 0.79 (b) 0.81 (c) 0.83 (d ) 0.85 (e) 0.88arrow_forward
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