Question

Use a psychrometric chart to determine the properties of air under different conditions.

1-Find the properties of air at 70 degrees F and 50% relative humidity. Find humidity ratio, wet bulb temperature, dew point, enthalpy, and specific volume.

2-Find the properties of air at 55 degrees F and 30% relative humidity. Find humidity ratio, wet bulb temperature, dew point, enthalpy, and specific volume.

3-Air enters a furnace at a dry bulb temperature of 60 degrees F and 50% relative humidity and leaves the furnace at a dry bulb temperature of 95 degrees F. Find the point that represents the condition of the air as it leaves the furnace. Identify humidity ratio, wet bulb temperature, dew point, enthalpy, and specific volume.

4-Air enters a furnace at a dry bulb temperature of 40 degrees F and 30% relative humidity and leaves the furnace at a dry bulb temperature of 80 degrees F. Find the point that represents the condition of the air as it leaves the furnace. Identify humidity ratio, wet bulb temperature, dew point, enthalpy, and specific volume.

5-Air enters a furnace at a dry bulb temperature of 40 degrees F and 30% relative humidity and leaves the furnace at a dry bulb temperature of 80 degrees F with the relative humidity being maintained at 30%. Find the point that represents the condition of the air as it leaves the furnace. Identify humidity ratio, wet bulb temperature, dew point, enthalpy, and specific volume.

Answer 1

In given question we are asked to find out the properties under given conditions we are as follows

Properties determined from psychrometry chart

Condition (Description)	Humidity ratio (grains of moisture per pound of dry air)	Wet bulb temperature (Degree F)	Due point temperature (Degree F)	Enthalpy (Btu / pound of dry air)	Specific Volume (ft3/lb)
1. 70 F & 50%RH	55	58.5	51	25.4	13.5
2. 55F & 30%RH	19.5	42	25	16	13.034
3. Heated in furnace 60F50% to 95F	38	63.75	41	29	14.125
4. Heated in furnace 40F30% to 80F	11	51	14	21.8	13.625
5. Heated in furnace 40F30% to 80F30% keeping RH constant	46	60	46	26.5	13.75

In furnace heating of air humidity ratio is kept constant and as the temperature increases the relative humidity decreases but in question 5 relative humidity is kept constant.

Conditions are represented on psychrometric chart given below.