Geothermal water, t_hi-95 c, is to be used in a double pipe counter-flow heat exchanger to heat cold water, tci-12 c, c,-41 80 j/kg-k flowing at l .2 kg/s to tc,-50 c for household use. the cold water will flow through the inner tube of the copper thin-walled heat exchanger, di 0.03761 m (1%"type k tubing). for safety reasons the size of the heat exchanger is to be limited in order to limit the outlet temperature of the cold water. assuming chot> ccold (note: c-m cp) and that the heat transfer coefficients on the hot and cold sides are approximately equal (hc -hh) what is the maximum allowable length of the heat exchanger? density of both streams is p 1000 kg/m', kter 0.615 w/m-k, h-0.798 x 10 kg/m-s, pr 5.4 (12.0 m)

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

Thermal stresses are developed in a metal when its a) initial temperature is changed b) final temperature is changed c) density is changed d) thermal deformation is prevented e) expansion is prevented f) contraction is prevented

Determine the damped natural frequencies and the steady state response of a decoupled damped forced two degrees of freedom system. 10ä1 + 2q1 20q1 10 cos t; 10q2 +4q2 + 40q2 10 cos t