3. A liquid that can be treated as water is being well mixed by a stirrer in a 1 m' vessel. The stirrer introduces 300 W of power into the vessel. The heat transfer from the tank to the surroundings is proportional to the temperature difference between the vessel and the surroundings (which are at 20°C). The flow rate of liquid in and out of the tank is 1 kg/min. If the temperature of the inlet liquid is 40°C, what is the temperature of the outlet liquid? The proportionality constant for the heat transfer is 100 W/°C.

A stream of ammonia is cooled from 100oC to 20oC at a rate of 180 kg/hr in the tube side of a double-pipe counter-flow heat exchanger. Water enters the heat exchanger at 10oC at a rate of 250 kg/hr. The outside diameter of the inner tube is 3 cm and the length of the pipe is 7m. Using the log-mean temperature difference, calculate the overall heat transfer coefficient (U) for the heat exchanger. Determine the log-mean temperature difference. Determine the heat transfer coefficient for the heat exchanger.   Cp for ammonia is 5234J/kgK and cp for water is 4180J/kgK.

A thin metal plate 1 mx 1 m is placed on a rooftop. It receives radiant heat from the sun directly at the rate of 170 W/m². If heat transfer from the plate to the ambient occurs purely by free convection, calculate the steady state temperature of the plate. Assume that there is no heat loss from the bottom of the plate. The ambient temperature is 25°C.

Steam enters a heat exchanger operating at steady state at 2 bar with a specific enthalpy of 1845 kJ/kg and exits at the same pressure as a saturated liquid. The steam mass flow rate is 1.6 kg/min. A separate stream of air with a mass flow rate of 68.5 kg/min enters at 37 °C and exits at 66.3 °C. The ideal gas model with c, = 1.005 kJ/kg.K can be assumed for air. Kinetic and potential energy effects are negligible.

Determine the efficiency for the cycle (standard air used as the working fluid) indicated in the sketch. Assume the pressures and temperatures are known quantities at each state. 1-2 constant volume process and 2-3 constant pressure process.

A stream of ammonia is cooled from 100oC to 20oC at a rate of 180 kg/hr in the tube side of a double-pipe counter-flow heat exchanger. Water enters the heat exchanger at 10oC at a rate of 250 kg/hr. The outside diameter of the inner tube is 3 cm and the length of the pipe is 7m. Using the log-mean temperature difference, calculate the overall heat transfer coefficient (U) for the heat exchanger. Determine the heat transfer rate between the two fluids. Determine the outlet temperature of the water. Determine the heat transfer surface area. Determine the log-mean temperature difference. Determine the heat transfer coefficient for the heat exchanger.   Cp for ammonia is 5234J/kgK and cp for water is 4180J/kgK.

3) A rigid tank (stationary) contains a hot fluid that is cooled while being stirred by a paddle wheel. Initially, the internal energy of the fluid is 800 kJ. During the cooling process, the fluid loses 500 kJ of heat, and the paddle wheel does 100 kJ of work on the fluid. Determine the final internal energy of the fluid. Neglect the energy stored in the paddle wheel.