A Waste Heat-Driven Cooling System Based on Combined Organic Rankine and Vapour Compression Refrigeration Cycles
Round 1
Reviewer 1 Report
The following questions/concerns should be resolved prior to publication.
Section 2, line 103: The abbreviation “MCR” needs to be explained/expounded upon. All the abbreviations, symbols and their units should be declared as a separate table at the beginning to enhance the readability of the manuscript.Figure 2 and line 103: The vertical axis towards the right of the figure is labelled as “heat capacity available in exhaust gas (kW)”. It is technically incorrect since heat capacity as a material property reported on per unit temperature basis (kJ/K) or in the case of specific heat capacity as kJ/kg K. Furthermore, as the exhaust gas temperature increases, the “heat capacity” has been shown to be decreasing. This is incorrect as well. With the increase in temperature, the translational, rotational and vibrational degrees of freedom increase for the gas molecules and this results in an increased heat capacity. Heat capacity of a gas always increases with the increase in temperature and then levels out at a maximum value once the available degrees of freedom have been saturated. It can never decrease with the increase in temperature as it would yield a negative value of the heat capacity.
Going by the description in line 105 and corroborating it with Figure 2, it appears that vertical axis on the right pertains to the “heat content” of the exhaust gas rather than “heat capacity”. It is suggested that the authors make these changes in the text and the figure.
Section 2.2.2: All the thermodynamic variables used should be depicted as state coordinates on a T-S or H-S plot to clearly depict all the major thermodynamic states attained by the working fluids in the conjugate systems.
Figure 3 depicts only selected points on the T-S plots, all the major thermodynamic states i.e. entry and exit points to/from the system components should be declared on the system schematic and on the T-S plots. Moreover, the plot does not have proper labeling of the temperature and entropy values, making it hard to ascertain the various processes plotted on it.
The authors need to be consistent with the temperature units that have been used throughout the study. Figure 2 and 3 have Temperature values reported in (C), however Figures 9,10,11,12 and 13 have the temperature values reported in (K).
Figure 11: Exergy loss in the evaporator for any cooling cycle is usually low compared to all other components. Exergy calculations done for Figure 11 need to be rectified and any inferences/conclusions drawn thereof need re-evaluation.
Recommendation
Major revisions.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors present a cogenerationsystem that consists from organic Rankine cycle and cooling cycle. The authors compare the work of the system in dependence of four refrigerants, and two gears. In one option there is belt drive with changed transmission ratio and the second variant in which there is a common shaft and transmission ratio is 1.
The general remark is that the coefficient of performance (COP) is the term that is applied in heat pumps, while in refrigeration engineering there is "energy efficiency ration" (EER). Please change the names and abbreviations in the paper, especially because of the fact that formula (33) defines EER.
The detailed remarks are written down hereinafter.
In the line 127 please calculate the constant "b".
In the line 137, should it be "pump" instead of "expander".
Line 138 and other hereafter: the subscript "s" is not defined.
The analysis of the formulas would be much easier if the authors plotted the lines of the processes in the entalpy-entropy chart or in the pressure-entalpy chart.
Line 230. Where do these fluids (refrigerants) work? Which one is in ORC cycle and which one is in VCC cycle?
The sentence in the lines 241 and 242 is unclear.
The sentence in the line 248 is unclear. Why "nevertheless" and when "decreases"?
The sentence in the lines 253 and 254. What does it mean "better performance"? Does it mean "more reliable"?
The lines 356-362. There is lack of the units under the abscissae.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The article is well written to describe the proposal on waste heat recovery from marine engine and utilise it in the cooling system. The literature is well described with proper reasoning and is fluent. The process and governing equations are presented clearly. The simulation results are well described and are clear to understand.
Author Response
Dear reviewer, many thanks for the comments concerning our manuscript.
Round 2
Reviewer 1 Report
None
