# Chapter10-Air conditioning¶

## Ex1-pg293¶

In [1]:
import math
## Example 10.1
print('Example 10.1\n\n');
print('Page No. 293\n\n');

## given
m = 1.;## mass flow rate of initial air mixture in kg/s
T = 23.5;## Initial temperature in degree celcius
m1 = 0.6;## Percentage of fresh air mixture
T1 = 5.;## Dry Bulb Temperature of  fresh air in degree celcius
w1 = 0.005;## Humidity  of fresh air at temperature T1 in kg/kg
m2 = 0.4;## Percentage of recirculated air mixture
T2 = 25.;## Dry Bulb Temperature of recirculated air in degree celcius
w2 = 0.015;## Humidity  of recirculated air at temperature T2 in kg/kg

##In air conditioning => m1*w1 + m2*w2 = m*w
w = (m1*w1 + m2*w2)/m;## in kg/kgs
print'%s %.2f %s'%('The humidity of the air mixture  is ',w,' kg/kg \n')

##The specific enthalpy in J/kg can be calculated by the formula => h = (1.005*10^3*T) +(w*((2.50*10^6)+(1.86*10^3*T))); where the T is the temperature and w is the humidity at temperature T
h_f = (1.005*10**3*T1) +(w1*((2.50*10**6)+(1.86*10**3*T1)));## Specific enthalpy of fresh air in J/kg
h_r = (1.005*10**3*T2) +(w2*((2.50*10**6)+(1.86*10**3*T2)));## Specific enthalpy of recirculated  air in J/kg
h_m = (1.005*10**3*T) +(w*((2.50*10**6)+(1.86*10**3*T)));## Specific enthalpy of  final air mixture in J/kg

h_t = (m1*h_f) + (m2*h_r);## Total enthalpy of initial air mixturein J/kg
Q = m*(h_m - h_t);## in Watts
print'%s %.2f %s'%('The load on the heater is ',Q,' W')
## Deviation in answer due to direct substitution and some approximation in answer in book

Example 10.1

Page No. 293

The humidity of the air mixture  is  0.01  kg/kg

The load on the heater is  10638.99  W


## Ex2-pg298¶

In [2]:
import math
## Example 10.2
print('Example 10.2\n\n');
print('Page No. 298\n\n');

## given
m1 = 0.75;## Percentage of fresh air mixture
T1 = 31.;## Dry Bulb Temperature of  fresh air in degree celcius
w1 = 0.0140;## Humidity  of fresh air at temperature T1 in kg/kg
m2 = 0.75;## Percentage of recirculated air mixture
T2 = 22.;## Dry Bulb Temperature of recirculated air in degree celcius
w2 = 0.0080;## Humidity  of recirculated air at temperature T2 in kg/kg
m = 1.50;## mass flow rate of final air mixture in kg/s
T = 10.;## Dew Point temperature in degree celcius

##In air conditioning => m1*w1 + m2*w2 = m*w
w = (m1*w1 + m2*w2)/m## in kg/kgs
print'%s %.2f %s'%('The humidity of the air mixture  is ',w,' kg/kg \n')

## from the psychrometric chart, at w = 0.011kg/kg, the  dry bulb temperature is = 26.5 degree celcius  also the humidity of saturated air at 10 degree celcius is 0.0075kg/kg
T_w = 26.5;## Dry Bulb temerature in degree celcius
w_10 = 0.0075;## humidity at temperatue T in kg/kg

##the specific enthalpy in J/kg can be calculated by the formula => h = (1.005*10^3*T) +(w*((2.50*10^6)+(1.87*10^3*T))); where the T is the temperature and w is the humidity at temperature T

h_a = (1.005*10**3*T_w) +(w*((2.50*10**6)+(1.88*10**3*T_w)));## Specific enthalpy of recirculated  air in J/kg
h_s = (1.005*10**3*T) +(w_10*((2.50*10**6)+(1.87*10**3*T)));## Specific enthalpy of saturated air at 10 degree celcius in J/kg

Q = m*(h_a - h_s);## in Watts
print'%s %.2f %s'%('The cooling load on the washer is ',Q,' W')
## Answer wrongly calculated in the book

Example 10.2

Page No. 298

The humidity of the air mixture  is  0.01  kg/kg

The cooling load on the washer is  38610.41  W