Solving Carnot Heat Problem: 1637.8BTU Answered

In summary, a heat engine connected to a 300 watt motor is operated for 4 hours. With a 40% efficiency, the heat extracted from the heat source can be calculated using the formula QH = W + QC. Using this equation, it can be determined that 4094.4 btuh of heat is extracted from the heat source during the 4 hour period. This means that the engine uses more heat energy than the work it yields, with the work being only 40% of the heat.
  • #1
Windseaker
46
0

Homework Statement


Problem: A heat engine is connected to a 300watt motor. If we power the motor for 4hrs and heat engine is 40% efficient,how much heat is extracted from heat source in?

Homework Equations


Given: Q= heat QC=waste heat QH=W+QC and Power=E/t or Work/t

The Attempt at a Solution

This is a diagram equation of heat.
QH-----l----->QC
l
l
V
300w

300W(3.412btu/1W)= 1023.6btu (4hr) = 4094.4 btuh
----- 4094.4btu(40%)=1637.8btuh
 
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  • #2
The engine uses more heat energy than the work it yields: the work is 40 % of the heat: W=0.4*Q.

Do you really use btu units for heat instead of joule?

ehild
 
  • #3
So, are you saying that time is not used here (4hrs)? its just the starting heat loss.

yes btu, this is more about residential usage in US.
 

Related to Solving Carnot Heat Problem: 1637.8BTU Answered

1. What is the Carnot Heat Problem?

The Carnot Heat Problem is a theoretical problem in thermodynamics that involves calculating the maximum possible efficiency of an ideal heat engine operating between two temperatures.

2. How is the Carnot Heat Problem solved?

The Carnot Heat Problem can be solved by using the Carnot cycle, which is a thermodynamic cycle that involves four processes: isothermal expansion, adiabatic expansion, isothermal compression, and adiabatic compression. By applying the laws of thermodynamics and using mathematical equations, the maximum efficiency of the Carnot cycle can be calculated.

3. What is the significance of solving the Carnot Heat Problem?

Solving the Carnot Heat Problem allows scientists and engineers to understand the theoretical limits of heat engines and to compare the efficiency of real-life heat engines to the ideal Carnot engine. It also provides insights into the efficiency of energy conversion processes and helps in the development of more efficient technologies.

4. What is the unit of measurement for the Carnot Heat Problem?

The Carnot Heat Problem is typically measured in British Thermal Units (BTU), which is a unit of energy commonly used in the United States. However, it can also be measured in other units such as joules or calories.

5. How is the Carnot Heat Problem applied in real life?

The Carnot Heat Problem has practical applications in various fields such as engineering, physics, and environmental science. It is used to analyze and improve the efficiency of power plants, refrigeration and air conditioning systems, and other energy conversion processes. It also plays a crucial role in the development of sustainable energy technologies.

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