jjc839
11-19-2006, 03:18 AM
A cyberprize :D to whoever can solve these first (and show it):
1.Consider a heating tank containing 20 kg water at initial temperature of 25*C. At starting time (t=0), an electrical heater producing 1000 W efficient energy to the water in the tank starts heating process and at the same time a stream of water with a flow rate of 5 m3/h at a constant temperature of 30*C enters the tank and a stream of water with 2 m3/h leaves the tank.
Assuming the process is adiabatic, the specific heat capacity of water remains constant at 4100 J/kg K and the density of water does not change during the process (=1000 kg/m3), predict the variation of temperature of the outlet water stream.
2.To provide hot water for a process, a simple tube heat exchanger is used. Water is allowed to flow through a tube, the wall of which is heated by steam. Assuming the temperature of tube (tube wall temperature) is kept constant at 100*C and the length and the mid diameter (average diameter for external and internal diameter of the tube) are 1 m and 30 cm, respectively, find a relationship between inlet water and outlet water temperature.
1.Consider a heating tank containing 20 kg water at initial temperature of 25*C. At starting time (t=0), an electrical heater producing 1000 W efficient energy to the water in the tank starts heating process and at the same time a stream of water with a flow rate of 5 m3/h at a constant temperature of 30*C enters the tank and a stream of water with 2 m3/h leaves the tank.
Assuming the process is adiabatic, the specific heat capacity of water remains constant at 4100 J/kg K and the density of water does not change during the process (=1000 kg/m3), predict the variation of temperature of the outlet water stream.
2.To provide hot water for a process, a simple tube heat exchanger is used. Water is allowed to flow through a tube, the wall of which is heated by steam. Assuming the temperature of tube (tube wall temperature) is kept constant at 100*C and the length and the mid diameter (average diameter for external and internal diameter of the tube) are 1 m and 30 cm, respectively, find a relationship between inlet water and outlet water temperature.