Document gbQN50OOwmM4xKpwzkBr8NZ7Q

>60 CHAPTER 3 ^ 1958 .Guide Solution b: From the A.S.H.A.E. Chart. (hi - h,)/(W, - ^i) yields i \ht-ht Wi -- Wt Solution of Equation 35 for the ratio t \ I (36) The slope of the condition line is therefore determined by the Enthalpy of the water which is supplied. This slope is established on the chart byjconnecting the center of the protractor on the psychrometric chart with the value of kw on the pro tractor. Draw a liae parallel to this reference line through the initial point 1 (Fig. 13). The second line is .the condition line for the process. Since thie conditions of the problem require the;final .point to lie on the saturation line, the intersection of the condition line with the-saturation line gives the desired solution. Adiabatic Saturation Adiabatic saturation is the designation given any process in which the state of moist air is changed from some initial unsaturated condition to a saturated one with- Thermodynamics i ti,UTg.AHO Fio. 13. Solution op Example 6 on A.S.H.A.E. Psychbometkic Chart out the addition or removal of heat. ' According to this definition, the addition of mdisture'to'ah adiabatic stream may become an adiabatic saturation process. Ex ample S is ah illustration. A type of adiabatic saturation of further practical interest is the use of continually recirculated spray water in a saturating air washer. Here the spray water will ultimately come to the same temperature as the saturated leaving air; this tempera ture is, by definition, the thermodynamic wet-bulb temperature. Hence, adiabatic saturation in this manner will have the final state point on the saturation curve, with the same thermodynamic wet-bulb temperature ais-the original state point. In a process such as this, the moist air enthalpy changes very slightly. The moisture added and temperature, change may be obtained from the psychrometric chart as sketched in Fig. 14..' Example 7: Moist air at 75 F dry-bulb temperature and 0.60 degree of saturation, is saturated adiabatically with recirculating spray water. Find the amount of water added and the change in enthalpy. Solution a: From the data of Table 2. As previously stated, the final tempera ture of the mixture will'be the thermodynamic wet-bulb temperature at the initial state. This must first be determined by the method of Example S, and is 65.51 F. At this temperature the humidity ratio at saturation and enthalpy at saturation are 0.01350 and 30.45, respectively. The humidity ratio at the initial state is 0.60(0.01882) = 0.01129; the initial enthalpy is 0.60(20.59).+ 18.018 = 30.372. The weight of water