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{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# Chapter 7 : Air Conditioning"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 7.1 Page no : 345"
]
},
{
"cell_type": "code",
"execution_count": 1,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Heating capacity of coil is 5.40 kW \n",
"Surface temperature of coil is 35 C \n",
"Capacity of humidifier is 3.33 kg/hr\n"
]
}
],
"source": [
"\n",
"# Variables\n",
"DBTo = 10.;\t\t\t#Out door Dry bulb temperature in oC\n",
"WBTo = 8.;\t\t\t#Out door Wet bulb temperature in oC\n",
"DBTi = 20.;\t\t\t#In door Dry bulb temperature in oC\n",
"RH = 0.6;\t\t\t#Re-Heat factor\n",
"a = 0.3;\t\t\t#amount of air circulated in (m**3)/min/person\n",
"S = 50.;\t\t\t#Seating capacity of office\n",
"BPF = 0.32;\t\t\t#ByPass factor\n",
"ha = 25.;\t\t\t#Enthalpy at point a from Psychrometric chart shown in Page 346 in kJ/kg\n",
"hb = 42.5;\t\t\t#Enthalpy at point b from Psychrometric chart shown in Page 346 in kJ/kg\n",
"hc = 42.5;\t\t\t#Enthalpy at point c from Psychrometric chart shown in Page 346 in kJ/kg\n",
"Wa = 0.006;\t\t\t#Specific humidity at point a from Psychrometric chart shown in Page 346 in kg/kg dry air\n",
"Wc = 0.009;\t\t\t#Specific humidity at point c from Psychrometric chart shown in Page 346 in kg/kg dry air\n",
"Tb = 27.;\t\t\t#Temperature at point b in oC\n",
"na = 0.81;\t\t\t#Specific Volume from Psychrometric chart shown in page 346 in (m**3)/kg\n",
"\n",
"# Calculations\n",
"ma = (a*S)/(na*60);\t\t\t#mass of air circulated per second in kg/s\n",
"Hc = ma*(hb-ha);\t\t\t#Heating capacity of coil in kW\n",
"Ts = (Tb-(BPF*DBTo))/(1-BPF);\t\t\t#Heating coil surface temperature in oC\n",
"C = (ma*3600)*(Wc-Wa);\t\t\t#Capacity of humidifier in kg/hr\n",
"\n",
"# Results\n",
"print 'Heating capacity of coil is %3.2f kW \\\n",
"\\nSurface temperature of coil is %3.0f C \\\n",
"\\nCapacity of humidifier is %3.2f kg/hr'%(Hc,Ts,C)\n",
"\n",
"# rounding off error"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 7.2 Page no : 346"
]
},
{
"cell_type": "code",
"execution_count": 2,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Capacity of cooling coil is 6.16 tonnes \n",
"Capacity of heating coil is 3.6 kW \n",
"Amount of water vapour removed per hour is 17.80 kg/hr \n",
"Bypass factor is 0.385\n"
]
}
],
"source": [
"# Variables\n",
"S = 60.;\t\t\t#No. of staff\n",
"DBTo = 30.;\t\t\t#Out door Dry bulb temperature in oC\n",
"RHo = 0.7;\t\t\t#Re-Heat factor at out-door\n",
"a = 0.4;\t\t\t#amount of air circulated in (m**3)/min/person\n",
"DBTi = 20.;\t\t\t#In door Dry bulb temperature in oC\n",
"RHi = 0.6;\t\t\t#Re-Heat factor at indoor\n",
"Td = 25.;\t\t\t#Heating coil surface temperature in oC\n",
"ha = 82.5;\t\t\t#Enthalpy at point a from Psychrometric chart shown in Page 347 in kJ/kg\n",
"hb = 34.5;\t\t\t#Enthalpy at point b from Psychrometric chart shown in Page 347 in kJ/kg\n",
"hc = 42.5;\t\t\t#Enthalpy at point c from Psychrometric chart shown in Page 347 in kJ/kg\n",
"Wa = 0.020;\t\t\t#Specific humidity at point a from Psychrometric chart shown in Page 347 in kg/kg dry air\n",
"Wb = 0.009;\t\t\t#Specific humidity at point b from Psychrometric chart shown in Page 347 in kg/kg dry air\n",
"Tb = 12.;\t\t\t#Temperature at point b in oC\n",
"na = 0.89;\t\t\t#Specific Volume from Psychrometric chart shown in page 346 in (m**3)/kg\n",
"\n",
"# Calculations\n",
"ma = (a*S)/(na*60);\t\t\t#mass of air circulated per second in kg/s\n",
"Hc = (ma*(ha-hb))/3.5;\t\t\t#Heating capacity of cooling coil in tonnes\n",
"Hh = ma*(hc-hb);\t\t\t#Heating capacity of heating coil in kW\n",
"W = (ma*3600)*(Wa-Wb);\t\t\t#Amount of water vapour removed per hour in kg/hr\n",
"BPF = (Td-DBTi)/(Td-Tb);\t\t\t#By-Pass factor\n",
"\n",
"# Results\n",
"print 'Capacity of cooling coil is %3.2f tonnes \\\n",
"\\nCapacity of heating coil is %3.1f kW \\\n",
"\\nAmount of water vapour removed per hour is %3.2f kg/hr \\\n",
"\\nBypass factor is %3.3f'%(Hc,Hh,W,BPF)\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example 7.3 Page no : 347"
]
},
{
"cell_type": "code",
"execution_count": 2,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"Supply air condition to the room is 2.74 kg/s \n",
"Refrigeration load due to reheat is 4.93 ton \n",
"Total refrigerating capacity is 16.28 ton \n",
"Quantity of fresh air supplied is 0.365 m**3/s\n"
]
}
],
"source": [
"\n",
"\n",
"# Variables\n",
"RSH = 10.;\t\t\t#Room sensible heat in kW\n",
"RLH = 10.;\t\t\t#Room latent heat in kW\n",
"td1 = 25.;\t\t\t#Inside temperature in oC\n",
"RH1 = 0.5;\t\t\t#Inside Re-Heat factor\n",
"h1 = 50.4;\t\t\t#Enthalpy at point 1 in kJ/kg\n",
"td2 = 35.;\t\t\t#Out door Dry bulb temperature in oC\n",
"tw2 = 28.;\t\t\t#Out door Wet bulb temperature in oC\n",
"CR = 4.;\t\t\t#Cooling coil ratio\n",
"BPF = 0.1;\t\t\t#Cooling coil bypass factor\n",
"tADP = 10;\t\t\t#Apparatus dew point temperature in oC\n",
"RH3 = 0.55;\t\t\t#Re-Heat factor at point 3\n",
"h3 = 58.2;\t\t\t#Enthalpy at point 3 in kJ/kg\n",
"RH4 = 0.95;\t\t\t#Re-Heat factor at point 4\n",
"h4 = 32.2;\t\t\t#Enthalpy at point 4 in kJ/kg\n",
"RH5 = 0.81;\t\t\t#Re-Heat factor at point 5\n",
"h5 = 36.8;\t\t\t#Enthalpy at point 5 in kJ/kg\n",
"RH6 = 0.54;\t\t\t#Re-Heat factor at point 6\n",
"h6 = 43.1;\t\t\t#Enthalpy at point 5 in kJ/kg\n",
"td6 = 22.;\t\t\t#Temperature at point 6 in oC\n",
"\n",
"# Calculations\n",
"td3 = ((td2-td1)/5)+td1;\t\t\t#Temperature at point 3 from Psychrometric chart shown in Page 348 in oC\n",
"td4 = (BPF*(td3-tADP))+tADP;\t\t\t#Temperature at point 4 from Psychrometric chart shown in Page 348 in oC\n",
"td5 = td4+((td1-td4)/5);\t\t\t#Temperature at point 5 from Psychrometric chart shown in Page 348 in oC\n",
"RSHF = RSH/(RSH+RLH);\t\t\t#Room Sensible Heat Factor\n",
"QR = h1-h6;\t\t\t#Total heat removed in kJ/kg\n",
"S = (RSH+RLH)/QR;\t\t\t#Supply air quantity in kg/s\n",
"R = (S*(h6-h5))/3.5;\t\t\t#Refrigeration load due to reheat in ton\n",
"D = (S*4)/5;\t\t\t#Dehumidified air quantity in kg/s\n",
"T = (D*(h3-h4))/3.5;\t\t\t#Total refrigerating capacity in ton\n",
"Q = (D/5)/1.2;\t\t\t#Quantity of fresh air supplied in (m**3)/s\n",
"\n",
"# Results\n",
"print 'Supply air condition to the room is %3.2f kg/s \\\n",
"\\nRefrigeration load due to reheat is %3.2f ton \\\n",
"\\nTotal refrigerating capacity is %3.2f ton \\\n",
"\\nQuantity of fresh air supplied is %3.3f m**3/s'%(S,R,T,Q)\n"
]
}
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