4. A mass of 1.7 kg of saturated liquid water is completely vaporized at a constant pressure of 101.325 kPa. Determine (a) the volume change and (b) the amount of energy transferred to the water.

Calculate the total energy, in kilojoules, that is needed to turn a 12 g block of ice at 0 degrees C into water vapor at 135 degrees C.

Evaporation Losses of Water in Irrigation Ditch. Water at 25°C is flowing in a covered irrigation ditch below ground. Every 100 ft there is a vent line 1.0 in. inside diameter and 1.0 ft long to the outside atmosphere at 25°C. There are 10 vents in the 1000-ft ditch. The outside air can be assumed to be dry. Calculate the total evaporation loss of water in lb/d. Assume that the partial pressure of water vapor at the surface of the water is the vapor pressure, 23.76 mm Hg at 25°C. Use the diffusivity from Table 6.2-1.

B) A mercury thermometer having a time constant of (90 sec) is initially at (300°C). It is immersed in a bath maintained at (130°C) at t = 0. Determine the temperature reading at (t=3 min) and (t = 5 min).

10.33 Saturated steam at 0.2 bar condenses with a convec- tion coefficient of 6000 W/m²2 · K on the outside of a brass tube having inner and outer diameters of 16 and 19 mm, respectively. The convection coefficient for water flowing inside the tube is 5000 W/m². K. Esti- mate the steam condensation rate per unit length of the tube when the mean water temperature is 30°C.

6. Determine the temperature of water at a state of P = 400 kPa and h = 3300 kJ/kg.

A 4.0-cm cube of aluminum is initially at 450◦C and is suddenly exposed to aconvection environment at 100◦C with h=120 W/m2 · ◦C. How long does it takethe cube to cool to 250◦C?

A 7 dm3 rigid tank contains 4.5 kg of saturated water (liquid and vapor) at 38ºC. The tank is slowly heated. a. After a long period of time what do you think happened to the liquid water surface: do you think it raised and reached the top of the tank or it dropped and reached the bottom of it? b. Solve the same problem considering that the amount of water is 0.45 kg instead.

Air is contained in a vertical piston–cylinder assembly fitted with an electrical resistor. The atmosphere exerts a pressure of 101.325 kPa on the top of the piston, which has a mass of 50 kg and a face area of 0.10 m 2 . Electric current passes through the resistor, and the volume of the air slowly increases by 2 ft3 while its pressure remains constant. The mass of the air is 0.32 kg, and its specific internal energy increases by 20 Btu/lb. The air and piston are at rest initially and finally. The piston–cylinder material is a ceramic composite and thus a good insulator. Friction between the piston and cylinder wall can be ignored, and the local acceleration of gravity is g = 32.0 ft/s2 Determine the heat transfer from the resistor to the air, in Btu, for a system consisting of (a) the air alone, (b) the air and the piston. Also draw the schematic diagram. Hint: Refer to example