Distribution Systems in Heating & Cooling
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Transcript of Distribution Systems in Heating & Cooling
Distribution Systemsin Heating and Cooling
Distribution Systems
Equipment and Materials Necessary for Conveying the Heating and Cooling Media
• Hydronic Systems• Storage Tanks• Steam Systems• Air Distribution Systems
Pipe InsulationRequired Data:• Length of Pipe• Pipe Diameter• Temperature of Fluid• Hours of Operation• Days in Heating Season
• Boiler Efficiency• Fuel Cost• Insulation Levels
– Existing– Proposed
Savings = Length x ∆ Heat Loss x Hours x 1 x $/Unit .of Pipe Length Year Eff. Wh/Unit
Minimum Piping InsulationSystemHeating
Temperature Range (°C)
Insulation Thickness,(mm)
High Pressure Steam 150-230 37,5-87,5
Medium Pressure Steam 120-148 32,5-75
Low Pressure Steam up to 119 25-50
Condensate 88-105 25-75
Hot Water over 93 25-75
Hot Water up to 93 12,5-37,5
Cooling
Chilled Water 4,5-13 12,5-25
Refrigerant and Brine Below 0 25-37,5
Pipe Insulation Problem
Required Data• 87 m of pipe • 37,5 mm diameter • 82 °C water • 24 hours/day• 240 days/year
• 80% efficiency • 0,0287 $/kWh• No insulation• Add 25 mm of
insulation
Cost savings = pipe length x ∆ Heat Loss x Hours x 1 x $ .Length Year Eff. kWh
Heat Loss with Uninsulated PipeW/m of pipe
Temperature of Water in Pipe (°C)37,8 48,9 60,0 65,6 82,0
Heat Loss (W/m of pipe) with no Insulation12,5 18,9 31,2 43,5 45,4 67,120,0 23,6 35,4 53,0 65,2 80,325,0 29,3 47,2 63,3 80,3 100,231,3 35,0 55,8 75,6 96,4 121,037,5 40,6 64,3 88,4 112,5 141,850,0 48,2 75,6 106,3 132,3 160,762,5 56,7 88,8 125,7 154,5 189,075,0 66,1 104,0 149,3 181,4 222,1Pipe
Dia
met
er (m
m)
Heat Loss with InsulationW/m of pipe
Temperature of Water in Pipe (°C)37,8 48,9 60,0 65,6 82,0
Heat Loss (W/m of pipe) with 25 mm of Insulation12,5 2,8 5,7 8,5 11,3 12,320,0 2,8 5,7 8,5 11,8 15,125,0 3,3 6,1 8,5 11,8 15,131,3 3,3 6,1 9,0 12,3 16,137,5 3,8 7,6 9,5 14,2 19,050,0 4,7 10,4 10,9 16,1 21,362,5 6,6 10,4 14,2 21,3 23,675,0 9,5 13,2 19,0 24,6 28,4Pipe
Dia
met
er (m
m)
Tank Insulation Example• Surface temperature (oC)• Room temperature (oC)• Annual hours• Boiler efficiency
• Tank length (m)• Tank diameter (m)• U values (1/R value),
(W/m2 oC)• Energy cost ($/kWh)
⎟⎟⎠
⎞⎜⎜⎝
⎛+×=
42
2DLDA ππ )(
D
L
Area for heat loss:
Savings = (Uold – Unew) x A x ∆T x Hours x $Efficiency x kWh
Duct Insulation
• Data Required– Length of duct (m)– Size of duct (m)– Operating hours/day– Operating days/year
– Ambient air temperature (oC)– Air temperature in duct (oC)– System efficiency– Cost per kWh
Energy Savings =
Area x ∆ W x hours x days x 1 x $ .m2 day year eff. kWh
Energy savings =area x ∆ W/m2 x hours
• Data Required– Length of duct (m)– Area per length of duct (m2/m) – Ambient air temperature (oC)– Air temperature in duct (oC)– Hours of operation– Cost per kWh
Duct Insulation Example
• 30 m duct run• No insulation • 12 hours/day• 240 days/year• Natural gas @ 0,0273 $/kWh
• 1 m x 0.3 m duct size• Add 37,5 mm of insulation• 48.8°C air in duct• 21°C plenum temperature• 80% furnace efficiency
30 m
FurnaceEff.: 80%Fuel
(Natural Gas)
Air Duct (48.8 °C air temp)
21 °C
Duct Insulation Example (cont...)• 30 m duct run• No insulation • 12 hours/day• 240 days/year• Natural gas @ 0,0273 $/kWh
• 1 m x 0.3 m duct size• Add 37,5 mm of insulation• 48.8°C air in duct• 21°C plenum temperature• 80% furnace efficiency
Energy Savings = Area x ∆ W x hours x days x 1 x $ .
m2 day year eff. kWh
Find from the chart