Determine the increase in energy cost of a 100-kW air compressor operating 8,000 hours per year due to a contaminated air filter. Assume that:
• The electrical motor efficiency is 90 percent.
• The pressure drop is 1.0 kPa for a clean air filter but becomes 3 kPa for a contaminated filter.
• The cost of electricity is $0.05/kWh.

Question

Accepted Answer

Using a rule of thumb, it can be stated that for every 1 kPa increase in the pressure drop across the air filter, the mechanical power is increased by 1 percent (because the mechanical power is proportional to the mass flow rate). Thus, the energy cost penalty $EC_{filter}$ , of using a contaminated air filter, can be estimated as follows:

$EC_{filter}=\frac {100kW * 8,000hrs/yr*\$0.05/k Wh}{0.90} *(\frac{3 kPa}{1kPa})*0.01=\$1.330/yr$

[latex]EC_{filter}=\frac {100kW * 8,000hrs/yr*\$0.05/k Wh}{0.90} *(\frac{3 kPa}{1kPa})*0.01=\$1.330/yr[/latex]

Question 11.2: Determine the increase in energy cost of a 100-kW air compre...

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