The Stirling Cycle
Storyboard 
A thermodynamic machine that doesn't rely on internal combustion but instead receives heat input externally. This process still generates the typical pressure-volume cycle, allowing for modeling and calculating the achieved efficiency.
ID:(1485, 0)
The Stirling Cycle
Description 
A thermodynamic machine that doesn't rely on internal combustion but instead receives heat input externally. This process still generates the typical pressure-volume cycle, allowing for modeling and calculating the achieved efficiency.
Variables
Calculations
Calculations
Equations
When supplying the heat supplied ($Q_H$), the temperature of the gas increases from $T_2$ to $T_3$ in an isochoric process (at constant volume). This implies that we can utilize the relationship for ERROR:8085 with the heat capacity at constant volume ($C_V$) and the variación de Temperature ($\Delta T$), expressed by the equation:
| $ dU = C_V \Delta T $ |
This results in the temperature in state 2 ($T_2$) and the temperature in state 3 ($T_3$) as follows:
| $ Q_h = C_V ( T_2 - T_1 )$ |
(ID 15363)
By removing the absorbed heat ($Q_C$) when the volume ($V$) equals the compressed volume ($V_2$), the absolute temperature ($T$) increases from the temperature in state 1 ($T_1$) to the temperature in state 2 ($T_2$). This implies that we can use the relationship for ERROR:8085 with the heat capacity at constant volume ($C_V$) and the variación de Temperature ($\Delta T$), which is expressed by the equation:
| $ dU = C_V \Delta T $ |
this leads us to the expression:
| $ Q_c = C_V ( T_1 - T_2 )$ |
(ID 15364)
The work is calculated using the integral of the work done on the system ($W_{in}$) with the number of moles ($n$) and the pressure ($p$), integrated in the volume ($V$), from the expanded volume ($V_1$) to the compressed volume ($V_2$):
| $ W = \displaystyle\int_{V_1}^{V_2}p\,dV$ |
If the pressure ($p$) is obtained using the universal gas constant ($R_C$), the number of moles ($n$), and the absolute temperature ($T$) with the gas equation
| $ p V = n R_C T $ |
the integral for the absolute temperature ($T$) is equal to the temperature in state 1 ($T_1$).
$W = \displaystyle\int_{V_1}^{V_2} p dV = \displaystyle\int_{V_1}^{V_2} \displaystyle\frac{nRT_1}{V} dV = nRT_1\ln\left(\displaystyle\frac{V_2}{V_1}\right)$
Therefore,
| $ W_{in} = n R_C T_1 \ln\left(\displaystyle\frac{ V_2 }{ V_1 }\right)$ |
(ID 15365)
The work is calculated using the integral of the work performed by the system ($W_{out}$) with the pressure ($p$), integrated in the volume ($V$), from the expanded volume ($V_1$) to the compressed volume ($V_2$):
| $ W = \displaystyle\int_{V_1}^{V_2}p\,dV$ |
If the pressure ($p$) is obtained using the universal gas constant ($R_C$), the number of moles ($n$), and the absolute temperature ($T$) with the gas equation
| $ p V = n R_C T $ |
the integral for the absolute temperature ($T$) is equal to the temperature in state 1 ($T_1$).
$W = \displaystyle\int_{V_1}^{V_2} p dV = \displaystyle\int_{V_1}^{V_2} \displaystyle\frac{nRT_2}{V} dV = nRT_2\ln\left(\displaystyle\frac{V_2}{V_1}\right)$
Therefore,
| $ W_{out} = n R_C T_2 \ln\left(\displaystyle\frac{ V_2 }{ V_1 }\right)$ |
(ID 15366)
(ID 15757)
The efficiency ($\eta$) is defined as the ratio of the effective work ($W$) to the heat contributed to the system ($Q$):
| $ \eta \equiv \displaystyle\frac{ W }{ Q } $ |
where the effective work ($W$) is related to the work performed by the system ($W_{out}$) and the work done on the system ($W_{in}$) through:
| $ W \equiv W_{out} - W_{in} $ |
while the heat contributed to the system ($Q$) is associated with the heat supplied ($Q_H$), which is defined as:
| $ Q \equiv W_{in} + Q_h $ |
As the work performed by the system ($W_{out}$) is related to the number of moles ($n$), the temperature in state 2 ($T_2$), the expanded volume ($V_1$), the compressed volume ($V_2$), and the universal gas constant ($R_C$) through:
| $ W_{out} = n R_C T_2 \ln\left(\displaystyle\frac{ V_2 }{ V_1 }\right)$ |
and the work done on the system ($W_{in}$) is associated with the temperature in state 1 ($T_1$) through:
| $ W_{in} = n R_C T_1 \ln\left(\displaystyle\frac{ V_2 }{ V_1 }\right)$ |
and the heat supplied ($Q_H$) is linked to the heat capacity at constant volume ($C_V$) by:
| $ Q_h = C_V ( T_2 - T_1 )$ |
the efficiency ($\eta$) can be calculated, resulting in:
| $ \eta = \displaystyle\frac{ T_2 - T_1 }{ T_1 + \displaystyle\frac{ C_V ( T_2 - T_1 )}{ n R_C \ln( V_2 / V_1 )}}$ |
(ID 15759)
Examples
ID:(1485, 0)
