How Is Heat Transferred During Gas Expansion in a Diesel Engine?

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In summary, these two questions involve calculations related to gas expansion at constant pressure. For the first question, we need to use Charles's law and the definitions of R and C_p to find the temperature, heat transferred, and work transferred. For the second question, we need to use the given law and formula to determine the final volume of the gas.
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junec21
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i have problem with these 2 questions.i been cracking my head the whole day about this/ anyone please help. please write down the steps for me if possible. thanks a lot in advance.

1) 0.25 kg of combustion gas in a diesel engine cylinder is at temperature of 727°C. The gas expands at constant pressure until its volume is 1.8 times its original value. For the combustion gas, R = 0.302 kJ/kgK and Cp = 1.09 kJ/kgK. Find the following:
a) temperature of the gas after expansion
b) heat transferred
c) work transferred

2) A quantity of gas has an initial pressure and volume of 0.1 MN/m2 and 0.1 m3, respectively. It is compressed to a final pressure of 1.4 MN/m2 according to the law pV1'26 = constant. Determine the final volume of the gas.
 
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junec21 said:
i have problem with these 2 questions.i been cracking my head the whole day about this/ anyone please help. please write down the steps for me if possible. thanks a lot in advance.
Hi Junec & welcome to PF,

What have you attempted thus far?
 
  • #3
junec21 said:
i have problem with these 2 questions.i been cracking my head the whole day about this/ anyone please help. please write down the steps for me if possible. thanks a lot in advance.

1) 0.25 kg of combustion gas in a diesel engine cylinder is at temperature of 727°C. The gas expands at constant pressure until its volume is 1.8 times its original value. For the combustion gas, R = 0.302 kJ/kgK and Cp = 1.09 kJ/kgK. Find the following:
a) temperature of the gas after expansion
b) heat transferred
c) work transferred

a)If you know it expands at constant pressure...What does that mean for Volume and Temperature? (Check what Charles's law says about it)
b)What is the definition of [itex]C_p[/itex]?
c) Do you know a formula for finding the Work done by a gas when it expands its volume at a constant pressure?
 

1. What is heat transfer and why is it important?

Heat transfer is the movement of thermal energy from one object to another due to a difference in temperature. It is important because it is essential for many natural and industrial processes, such as cooking, heating and cooling systems, and chemical reactions.

2. What factors affect the amount of heat transferred?

The amount of heat transferred depends on the temperature difference between the two objects, the specific heat capacity of the materials involved, the surface area of contact, and the duration of contact.

3. How is heat transferred?

Heat can be transferred through three different methods: conduction, convection, and radiation. Conduction is the transfer of heat through direct contact between two objects. Convection is the transfer of heat through the movement of fluids or gases. Radiation is the transfer of heat through electromagnetic waves.

4. What is the unit of measurement for heat transfer?

The unit of measurement for heat transfer is joules (J), which is a measure of energy. It can also be measured in calories (cal) or British Thermal Units (BTUs).

5. How can heat transfer be calculated?

The amount of heat transferred can be calculated using the formula Q = mcΔT, where Q is the heat transferred, m is the mass of the object, c is the specific heat capacity, and ΔT is the change in temperature. This formula applies to conduction and convection. For radiation, the Stefan-Boltzmann law can be used to calculate the heat transfer based on the temperature and surface area of the objects.

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