250
B. Yang
Fig. 2. Effect of combination of operating parameters on cycle efficiency in a two-loop system
3.2 Run Characteristics of Rankine Cycle with Exhaust Preheating
By using the design value of the parameters of the two-loop system with air extraction
preheating for MATLAB modeling, the extraction volume is 11.4 and the cycle efficiency
is only 24.20, and the calculation error is large because the detailed parameters of the
system are not perfect. The extraction rate is changed and the reasons are analyzed.
The work done by turbine feed pump is neglected, but the high temperature steam
after preheater does not work directly condensing, the drawback is not only the waste
of energy, but also the increase of equipment complexity caused by different pressure of
the two working fluids.
The limitation of temperature rise at cold end of heat exchanger leads to insufficient
utilization of extraction energy; The lower the extraction volume, the higher the cycle
efficiency, and the efficiency advantage is when the extraction rate is less than 5.
In addition, the effect of changing the temperature of the preheater on the efficiency
is shown in Fig. 3. It can be found that the increase of temperature rise at the cold end
of the heat exchanger can effectively improve the Rankine cycle efficiency with exhaust
gas, and the two are almost linearly related.
Fig. 3. Effect of changing the temperature
Fig. 4. Effect on cycle efficiency
B. Yang
Fig. 2. Effect of combination of operating parameters on cycle efficiency in a two-loop system
3.2 Run Characteristics of Rankine Cycle with Exhaust Preheating
By using the design value of the parameters of the two-loop system with air extraction
preheating for MATLAB modeling, the extraction volume is 11.4 and the cycle efficiency
is only 24.20, and the calculation error is large because the detailed parameters of the
system are not perfect. The extraction rate is changed and the reasons are analyzed.
The work done by turbine feed pump is neglected, but the high temperature steam
after preheater does not work directly condensing, the drawback is not only the waste
of energy, but also the increase of equipment complexity caused by different pressure of
the two working fluids.
The limitation of temperature rise at cold end of heat exchanger leads to insufficient
utilization of extraction energy; The lower the extraction volume, the higher the cycle
efficiency, and the efficiency advantage is when the extraction rate is less than 5.
In addition, the effect of changing the temperature of the preheater on the efficiency
is shown in Fig. 3. It can be found that the increase of temperature rise at the cold end
of the heat exchanger can effectively improve the Rankine cycle efficiency with exhaust
gas, and the two are almost linearly related.
Fig. 3. Effect of changing the temperature
Fig. 4. Effect on cycle efficiency