Energy & Cost Savings
EXAMPLE OF ONE MYLAR RHE2750 WHEEL FREE HEATING 8,000 L/S FRESH AIR IN A MELBOURNE INDOOR POOL
Met. Statistical Data for Melbourne calculated by CSIRO and published by AIRAH.
Taking a typical Aquatic Pool in Melbourne with an indoor average Pool Hall temperature 27 C, using the data analysis from the above reference shows that in order to raise ambient air to 27 C requires a total 128,375 kWh per annum per m3/s air flow. Note for any higher Pool Hall temperature savings would be higher.
ENERGY & COST SAVINGS FOR BALANCED FLOW (EQUAL EXHAUST & FRESH AIR) OF 8,000 l/s USING ONE S426RHE2750 2750mm Dia SERIES 426 HIGH PERFORMANCE MYLAR ROTARY HEAT EXCHANGER
PERFORMANCE 83% Heat Recovery at 173 Pa air flow pressure drop
ESTIMATED ANNUAL ENERGY SAVED
1 kWh = 3.6 MJ = 3.6 GJ/1000
Energy Saved = 3.6 x 8 x 128,375 x 0.83 GJ
= 3,069 GJ
Natural gas required to heat air using a conventional boiler and hot water heat exchanger system assuming a 75% overall efficiency for air heating would require
Natural Gas Savings = 3,069/0.75 = 4,092 GJ Natural Gas
ESTIMATED N.G ENERGY COST SAVINGS
For a NG cost of $10/GJ Annual NG Cost Savings is
= 4,092 x 10
= $40,920 pa
ELECTRICAL FAN POWER ATTRIBUTED TO RHE FAN USE
FLOW x PRESSURE DROP/ FAN EFFICIENCY
FRESH AIR SIDE 8.000 x 173/0.75 = 1845 We
EXHAUST AIR SIDE 8.000 x 173/0.75 = 1845 We
TOTAL parasitic power loss = 3.69 kWe
Assuming 8,000 h/a operation total fan energy used = 29,520 kWh
Assuming a 20c/kWh cost of electricity = 29,520 x 0.20 = $5,904 pa
Thus reducing savings to $40,920 – $5,904 = $35,016 pa
This results in a less than 1 year payback on the cost of the Rotary Heat Exchanger excluding installation costs.
Maintenance costs for the Mylar wheel is very low and they have a proven long life in aquatic environments.
The $ savings will double to $70,000 per annum, if gas cost rises to $20 per GJ resulting in a less than 6 months payback. Todays domestic prices in Victoria exceed this gas price.
ANNUAL GREENHOUSE GAS EMISSIONS REDUCTION
Ref: Australian Govt Department of Climate Change
For Vic NG GGE is 57.3 kg CO2-e/GJ Resulting in 4,092 x 57.3/1000 = 234.5 t CO2-e emission reduction per annum.
For Vic Electricity GGE is 1.31 kg CO2-e/kWhe Resulting in 1.31 x 29,520/1000 = 38.7t CO2-e emission increase per annum.
NET REDUCTION IN GGE
= 234.5 - 38.7 = 195.8 t CO2-e emission reduction per annum.