CFD Simulation Analysis on Make-up Air Supply by Distance from Cookstove for Cooking-Generated Particle

Round 1

Reviewer 1 Report

This paper describes a case study on the CFD simulation analysis on make-up air supply by distance from cookstove for cooking-generated particles in Korean typical house. The simulation results provided useful suggestions on the way of installation of the auxiliary supply system. However, several points should be justified before acceptance.

• The CFD simulation was conducted when the ventilation system was deactivated. As authors described, the effect of auxiliary supply system can be singled out under this condition. However, are there any persons who actually dare to cook in the house without any ventilation? I believe this CFD simulation should be conducted when the ventilation system is on. Please provide more comments or description on this point.
• As described in Page 3, line 73-74, PM_2.5 concentration was measured for validation of the CFD simulation. However, I can not find the result in this manuscript. Why omitted?
• In page 7, line 167, authors described the temperature above the cookstove was kept constant at 163 degC. My simple question is whether the temperature is enough to produce PM from foods. For example, the smoke temperature (smoking point) of beef tallow is 220 degC. Please explain why authors fixed the temperature at 163 degC.
• The CFD model developed in this study seems to work well for simulations of CO₂ and temperature in the house, as described by authors. However, behavior of PM in indoor environment is quite different with that of CO₂. The PM does not simply emit from food and spread in indoor air. As for emission, secondary formation of PM from gaseous components should be considered because the gases emitted form cooking are cooled in indoor air to form particles. While the CO₂ is almost inert to interior materials, PM tends to sink on the ceiling or walls by adsorption. Have authors considered such differences between CO₂ and PM in this simulation?
• Highlight of the research results or conclusion should be included in abstract.

Author Response

We are grateful to the reviewers for a very thorough review and constructive comments. The comments are listed below with our responses. We have revised the manuscript based on reviewers’ comments. We hope that our responses and the changes in the revised manuscript are sufficient for the reviewers.

1. As described in Page 3, line 73-74, PM2.5 concentration was measured for validation of the CFD simulation. However, I can not find the result in this manuscript. Why omitted?

2. 
   In page 7, line 167, authors described the temperature above the cookstove was kept constant at 163 degC. My simple question is whether the temperature is enough to produce PM from foods. For example, the smoke temperature (smoking point) of beef tallow is 220 degC. Please explain why authors fixed the temperature at 163 degC.

3. 
   The CFD model developed in this study seems to work well for simulations of CO2 and temperature in the house, as described by authors. However, behavior of PM in indoor environment is quite different with that of CO2. The PM does not simply emit from food and spread in indoor air. As for emission, secondary formation of PM from gaseous components should be considered because the gases emitted form cooking are cooled in indoor air to form particles. While the CO2 is almost inert to interior materials, PM tends to sink on the ceiling or walls by adsorption. Have authors considered such differences between CO2 and PM in this simulation?

4 Highlight of the research results or conclusion should be included in abstract.

Reviewer 2 Report

This paper presented a computational fluid dynamics (CFD) study on the influence of the variant locations of the supply diffuser on the spread of cooking-generated particular matter (PM). The CFD simulations were performed based on the Reynolds-averaged Navier-Stokes (RANS) turbulence model, and validated against experimental measured room temperatures at different measurement locations and carbon dioxide (CO2) concentrations. Lastly, suggestions on the optimal installation location of the supply diffuser were provided. Overall, this paper is fairly well-written with a moderate amount of analysis and discussions. The conclusion is solid and well supported by the results. I recommend publishing this paper after the following issues being resolved.

1. Please consider improving the resolution of several figures, as their current resolution may be slightly lower for publication purpose. They are Figures 1, 5, 6, 7, and 10.
2. Please provide more description on Figure 2. For example, what does P1, P2, and P3 stand for?
3. In Section 2.2, does the CO2 concentration measured at the same locations where temperatures were measured? Please briefly describe the CO2 measurement location(s) in this section.
4. In Section 3, please briefly describe the boundary conditions specified for the CFD simulation.
5. The sentence in Line 162-163 seems to be problematic. How to compare the temperature data WITH carbon dioxide concentration data? Do the authors mean “simulation was validated by comparing simulated room temperatures and carbon dioxide concentrations with the experimental measured data?”
6. In Figure 6, does each experimental data at a given height represent an averaged value of temperatures taken at different wall locations at the same height? Could the authors provide error bars of the experimental data? Moreover, please explain in the text, why the discrepancies of simulated and measured data becomes larger at higher height?
7. Similarly, in Figure 7, if CO2 concentrations were measured at multiple locations in kitchen and living room, please indicate the value (bar) presented is an average (or some other statistical quantities) and provide error bars.
8. Please center the caption of Figure 8.

Author Response

We are grateful to the reviewers for their very thorough review and constructive comments. The comments are listed below with our responses. We have revised the manuscript based on the reviewers’ comments. We hope that our responses and the changes made in the revised manuscript are sufficient.

1. Please consider improving the resolution of several figures, as their current resolution may be slightly lower for publication purpose. They are Figures 1, 5, 6, 7, and 10.

2. 
   Please provide more description on Figure 2. For example, what does P1, P2, and P3 stand for?

3. 
   In Section 2.2, does the CO2 concentration measured at the same locations where temperatures were measured? Please briefly describe the CO2 measurement location(s) in this section.

4. 
   In Section 3, please briefly describe the boundary conditions specified for the CFD simulation.

5. The sentence in Line 162-163 seems to be problematic. How to compare the temperature data WITH carbon dioxide concentration data? Do the authors mean “simulation was validated by comparing simulated room temperatures and carbon dioxide concentrations with the experimental measured data?”

6. In Figure 6, does each experimental data at a given height represent an averaged value of temperatures taken at different wall locations at the same height? Could the authors provide error bars of the experimental data? Moreover, please explain in the text, why the discrepancies of simulated and measured data becomes larger at higher height?

7. Similarly, in Figure 7, if CO2 concentrations were measured at multiple locations in kitchen and living room, please indicate the value (bar) presented is an average (or some other statistical quantities) and provide error bars.

8. Please center the caption of Figure 8.

Round 2

Reviewer 1 Report

The manuscript has been properly corrected considering reviewer's comments.