Calculate the amount of natural gas required to heat the water in a heater.
Answer to Problem 41P
The amount of natural gas required to heat the water in a heater is
Explanation of Solution
Given data:
Volume of water used per day is
Initial temperature of water is,
Final temperature of water is,
Efficiency of heater is
From Table 11.13 in the textbook, the specific heat of water is,
Standard density of water is
Formula used:
The relationship between degree Fahrenheit and degree Celsius is,
Here,
The formula to find thermal energy required to heat the water is,
Here,
Calculation:
Convert the unit of volume of the water,
Substitute
Substitute
The expression to find the mass of the water is,
Substitute
The unit conversion on above result is,
Do the unit conversion on above result,
At standard
Then the amount of natural gas required to heat the water in heater can be determined from the below expression:
Therefore, the amount of natural gas required to heat the water in a heater is
Conclusion:
Hence, the amount of natural gas required to heat the water in a heater is
Want to see more full solutions like this?
Chapter 11 Solutions
ENGINEERING FUNDAMENTALS
- For a building located in London, England with annual heating degree-days (dd) of 5634, a heating load (heat loss) of 42,000 kj/h, and a design temperature difference of 35° C (20° C indoor), estimate the annual energy consumption. If the building is heated with a furnace with an efficiency of 98%, how much gas is burned to keep the home at 20° C? State yourassumptions.arrow_forwardA heat pump supplies heat energy to a house at the rate of 140,000 kJ/h when the house is maintained at 25°C. Over a period of one month, the heat pump operates for 100 hours to transfer energy from a heat source outside the house to inside the house. Consider a heat pump receiving heat from two different outside energy sources. In one application the heat pump receives heat from the outside air at 0°C. In a second application the heat pump receives heat from a lake having a water temperature of 10°C. If electricity costs $0.105/kWh, determine the maximum money saved by using the lake water rather than the outside air as the outside energy source.arrow_forwardA room has a width of 14.1 feet, a length of 14.8 feet, and a ceiling height of 14 ft. The average flow rate for this room's air conditioning unit is 3.7 m3/s. How many hours will it take for the air conditioner to cycle the volume of air in the room?arrow_forward
- When 1 cu ft of natural gas is burned, 1,050 Btu of heat are produced. In oneday, a building uses 761,250 Btu of heat. How many cubic feet of gas areburned?arrow_forwardDetermine the energy consumption (BTU/min), If two 50-kg LPG tanks are needed per 24-hour operation, heating value for the LPG of 11,000 kcal/kg. Subject: Civil Engineering: Thermodynamicsarrow_forwardThe Energy Efficiency Rating (EER) of an air-conditioning unit is defined asthe ratio of the heat removed in Btu/h divided by the energy used in watts.The EEI (Edison Electric Institute) names an air-conditioning unit as anEnergy Star unit if it has an EER of 13 or greater. A 21⁄2-ton air-conditioningunit uses 2.41 kilowatts (2,410 watts) of energy. One ton is equivalent to12,000 Btu/h. Can this unit be termed an Energy Star unit?arrow_forward
- Q1; If a system has 30J of heat added to it, and the total change in its internal energy is 10J, how much work does it do? a- 70 J b- 0.0 J c- 10J d- 20 J e- 10 Jarrow_forwardReplacing incandescent lights with energy-efficient fluorescent lights can reduce the lighting energy consumption to one-fourth of what it was before. The energy consumed by the lamps is eventually converted to heat, and thus switching to energy-efficient lighting also reduces the cooling load in summer but increases the heating load in winter. Consider a building that is heated by a natural gas furnace with an efficiency of 80 percent and cooled by an air conditioner with a COP of 3.5. If electricity costs $0.12/kWh and natural gas costs $1.40/therm (1 therm = 105,500 kJ), determine if efficient lighting will increase or decrease the total energy cost of the building (a) in summer and (b) in winter.arrow_forwardCalculate the energy lossarrow_forward
- A classroom that normally contains 40 people is to be air-conditioned with window air-conditioning units of 5-kW cooling capacity. A person at rest may be assumed to dissipate heat at a rate of about 360 kJ/h. There are 10 lightbulbs in the room, each1 with a rating of 100 W. The rate of heat transfer to the classroom through the walls and the windows is estimated to be 15,000 kJ/h. If the room air is to be maintained at a constant temperature of 21°C, determine the number of window air-conditioning units required.arrow_forwardCompare the masses and volumes of water, concrete, sand, and wood needed to store 106 Btu of heat if the operating temperatures are Tc = 85F and Th = 180F. In each case, calculate the edge length of a square storage unit with a height of 8 ft.arrow_forward
- Engineering Fundamentals: An Introduction to Engi...Civil EngineeringISBN:9781305084766Author:Saeed MoaveniPublisher:Cengage Learning