3. Engineering Economics & Environmental Questions (10 points) (ACCE-SLO#18)

Your Company plans to purchase a 10-ton A/C to replace an existing unit. It costs $15,000 to install. It is high-efficiency equipment, which meets the requirement of SCEs rebate program of $50 per ton/year for the first two years. The expected yearly energy saving is $4,000 with 4% escalation rate. The estimated yearly repair/maintenance fee is $1,000 with 2% escalation rate; Assume 5% discount rate, please find out:

a). Simple Pay back

b). Life-Cycle cost by showing accumulative present values for the next 5 years.

c). Utility savings from the above unit will help to reduce pollutants liberated to the atmosphere. If current electric rate is $0.14/kwh, how many pounds of CO2 yearly will be reduced due to the electric savings from it? (Assume electric generated bygas)

4. Cooling Questions (3 points) (ACCE-SLO#20)

a). Describe the basic difference between unitary and split DX systems

b). Under what circumstances would an absorption water chiller be an economical choice with the respect to the energy cost of its operation?

c). How much chilled water would be required to reduce chiller load by 200 tons for a period of 6 hours? How much is for ice storage?

5. Heating Questions (2 points) (ACCE-SLO#20)

a). In the State of Idaho, gas is available at $0.74/Therm and electric is available $0.074/kwh. Calculate to show which will be the more economical fuel source on the basis of cost per Btu (assume 100% utilization efficiency for both)

b). List your observations from Solar Collector Efficiency Curve