Question

SKMM 2423 QUESTION 4 a) Cold water flows through a metal pipe, which is not insulated The pipe is loc ated in am ambient air, which is at a higher temperature and humidity, What do you think would be observed on the surface of the pipe? Describe briefly the reason for this 5 marks) b) A sling psychrometer shows a dry bulb and wet bulb temperature readings of 25°C and 20°C, respectively. The atmospheric pressure is 101 325 kPa. Using the psychrometric chart and by calculation, determine ) the specific humidity, g wrg da ii) the relative humidity, 96, -P im) the partial pressure of water vapor and dry air, kPa iv) the dew point temperature, C v) the specifie enthalpy, da. and the percentage saturation of the air, % vi) 8 marks) c) The atmospheric air in part (b) above is cooled at constant pressure until it becomes saturated at a temperature of 10°C. The air is then heated at a constant pressure until its dry bulb temperature rises to 18°C. Show the paths of these processes on the psychrometric chart provided. Using the chart, determine ) the final specific humidity, Ag w.v.kg da the final relative humidity, % ii) iii) the final wet bulb temperature, t. iv) the final percentage saturation of the air, %. v) the mass of condensate collected at the cooler, kg w.wikg da. vi) the heat rejected from the air during the cooling process, kJlkg da, and vin) the heat added to the air during the heating process, kJ/kg da (12 marks)

Answer 1

From-the-bachtom done chart. t-- Relative-humidibLS-63-22 49 0 turun :..hg. ,)/ ,よろ,. 制,, Enthalbu Aatation62 1823 chal