A car wash service uses 150 litre of pressurized (3 bar) warm water (45oC) to wash each car. It takes 10 min to wash each car. The service has 10 washing lanes, and it is open from (14:00 to 21:00) every day and 360 day per year. Each day 400 cars are washed. Fresh water at 1 bar pressure and 15oC is pressurized in a pump and then heated to desired temperature. Assume pump operates adiabatically and its efficiency is 85%, which is defined as the ideal power input divided by the actual power input. The ideal power input is the product of the volumetric flow rate times the pressure drop across the pump. All the other equipment of the car wash uses 5 kW of power during operation. Current (first alternative) is to buy electricity from the utility and use a natural gas fired boiler to heat the water.  Assume natural gas furnace used in heating has 90% overall efficiency defined as heating provided water to heating released from fuel. The heating value of the natural gas (CH4) is 55.5 MJ/kg, its molecular weight is 16, its adiabatic flame temperature is 2230 K, and its energy is 824,350.0 kJ/kmol. Natural gas costs $0.52/kg. Electricity cost from the utility is $0.16/kWh. The utility is required to produce 10% of its electricity by green (no CO2 producing) processes by state law and the other 90% using natural gas.  You do not need to know the cost of fuel oil because it is included in the electricity cost. The yearly cost of operating and maintaining this system is $0.005 /kWh of energy used (note this cost is per output energy).  City asks $9.794 per 1000 gallons of fresh water, and $13.759 per 1000 gallons of drained water. Cost of natural gas based heating system is $27000 with 15 years lifetime. Cost of each pump is $1600 including installation with 7.5 years lifetime. For this alternative determine: 1. The required electrical power and natural gas to operate this system using the first law energy balance. 2. The energy destroyed in the pump and washing systems using the energy balance. Assume water used to wash the car end up in surrounding conditions once is drained. 3. The second law efficiency of the pump heater system. 4. Yearly production of carbon dioxide produced. In your solution, include the chemical reaction equation used to determine the ratio of the CO2 produced to the fuel input as well as the one produced by the utility for the power input. 5. The thermo economic cost washing cars (on a yearly basis). INFORMATION FOR ALTERNATIVE SOLUTIONS The heating value of the natural gas (CH4) is 55.5 MJ/kg, its molecular weight is 16, its adiabatic flame temperature is 2230 K, and its energy is 824,350.0 kJ/kmol. A gas fired boiler for this application costs $27,000 and has an efficiency of 90% The cost of a co-generation in this size range is $123,000 and has a life expectancy of 15 years. The installed solar PV collector cost for a 1.88 m2 is $4,500 with a 15-year lifetime and an efficiency of 13%. An average condition can be used for this analysis for the incident solar radiation. The average incident solar rate for the year is 543 W/m2 and the average day length is 10 hours. The battery cost is $65 per battery with a lifetime of 3 years. Each battery is rated at 12 volts, with a maximum continuous current of 5.2 amps and has a rated at energy storage of 105 amp-hours. Battery throughput efficiency (Charge-Discharge cycle) is 81%. This efficiency equals the energy output from the battery divided by the energy input. Battery charger circuit per collector is $500, has a lifetime of 25 years, and an efficiency of 0.91. This is in addition to charging efficiency of batteries. The boiler/heat exchanger can directly use the solar collector output and/or battery output and is the same cost and lifetime as that in the first alternative. There is a onetime federal tax credit of 15% of the solar installation cost that applies to this plan. The property taxes on the land used for the solar collectors are $5.00/m2 per year for this land.

Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
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A car wash service uses 150 litre of pressurized (3 bar) warm water (45oC) to wash each car. It takes 10 min to wash each car. The service has 10 washing lanes, and it is open from (14:00 to 21:00) every day and 360 day per year.

Each day 400 cars are washed. Fresh water at 1 bar pressure and 15oC is pressurized in a pump and then heated to desired temperature.

Assume pump operates adiabatically and its efficiency is 85%, which is defined as the ideal power input divided by the actual power input. The ideal power input is the product of the volumetric flow rate times the pressure drop across the pump.

All the other equipment of the car wash uses 5 kW of power during operation. Current (first alternative) is to buy electricity from the utility and use a natural gas fired boiler to heat the water.

 Assume natural gas furnace used in heating has 90% overall efficiency defined as heating provided water to heating released from fuel.

The heating value of the natural gas (CH4) is 55.5 MJ/kg,

its molecular weight is 16,

its adiabatic flame temperature is 2230 K,

and its energy is 824,350.0 kJ/kmol.

Natural gas costs $0.52/kg.

Electricity cost from the utility is $0.16/kWh.

The utility is required to produce 10% of its electricity by green (no CO2 producing) processes by state law and the other 90% using natural gas.

 You do not need to know the cost of fuel oil because it is included in the electricity cost. The yearly cost of operating and maintaining this system is $0.005 /kWh of energy used (note this cost is per output energy).

 City asks $9.794 per 1000 gallons of fresh water, and $13.759 per 1000 gallons of drained water.

Cost of natural gas based heating system is $27000 with 15 years lifetime.

Cost of each pump is $1600 including installation with 7.5 years lifetime.

For this alternative determine:

1. The required electrical power and natural gas to operate this system using the first law energy balance.

2. The energy destroyed in the pump and washing systems using the energy balance. Assume water used to wash the car end up in surrounding conditions once is drained.

3. The second law efficiency of the pump heater system.

4. Yearly production of carbon dioxide produced. In your solution, include the chemical reaction equation used to determine the ratio of the CO2 produced to the fuel input as well as the one produced by the utility for the power input.

5. The thermo economic cost washing cars (on a yearly basis).

INFORMATION FOR ALTERNATIVE SOLUTIONS

  • The heating value of the natural gas (CH4) is 55.5 MJ/kg, its molecular weight is 16,
  • its adiabatic flame temperature is 2230 K, and its energy is 824,350.0 kJ/kmol.
  • A gas fired boiler for this application costs $27,000 and has an efficiency of 90%
  • The cost of a co-generation in this size range is $123,000 and has a life expectancy of 15 years.
  • The installed solar PV collector cost for a 1.88 m2 is $4,500 with a 15-year lifetime and an efficiency of 13%.
  • An average condition can be used for this analysis for the incident solar radiation. The average incident solar rate for the year is 543 W/m2 and the average day length is 10 hours.
  • The battery cost is $65 per battery with a lifetime of 3 years. Each battery is rated at 12 volts, with a maximum continuous current of 5.2 amps and has a rated at energy storage of 105 amp-hours.
  • Battery throughput efficiency (Charge-Discharge cycle) is 81%. This efficiency equals the energy output from the battery divided by the energy input. Battery charger circuit per collector is $500, has a lifetime of 25 years, and an efficiency of 0.91. This is in addition to charging efficiency of batteries.
  • The boiler/heat exchanger can directly use the solar collector output and/or battery output and is the same cost and lifetime as that in the first alternative.
  • There is a onetime federal tax credit of 15% of the solar installation cost that applies to this plan.
  • The property taxes on the land used for the solar collectors are $5.00/m2 per year for this land.
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