The Mathematical Modeling, Diffusivity, Energy, and Enviro-Economic Analysis (MD3E) of an Automatic Solar Dryer for Drying Date Fruits

Round 1

Reviewer 1 Report

This is an interesting simple paper that Mathematical Modeling, Energy, Enviro-Economic Analysis of an Automatic Solar Dryer for Drying Date Fruits. PV System and IoT Technology are in very high demand of food science. However, there are some missing information regarding results and methods in some experiments.

1.     The authors stated (line 205): «The sample has been assumed to be initially uniformly distributed with moisture, to have constant thermo-physical prop- erties, to shrink or deform minimally during drying, to have a spherical shape, to have negligible resistance to transfer in the medium surrounding the sphere, to generate negli- gibly little heat inside the moist sample, and to have negligible radiation effects».

Why do authors used a spherical shape instead of cylindrical shape? Cylindrical shape is more suitable and acceptable for a Drying Date Fruits.

2.     Mathematical solution of eq (6)-(20) is well known. I didn’t find any novel assumption. So this part can be neglected.

3.     Again. Section is also well-known data. The authors no need to declare a well know data.

A detailed mathematical solution can be find https://books.google.ru/books?id=xP5vEAAAQBAJ&lpg=PA185&ots=X5haQ_WzmF&dq=fick%20for%20cylinder%20drying%206%2F%F0%9D%9C%8B2&hl=ru&pg=PA185#v=onepage&q=fick%20for%20cylinder%20drying%206/%F0%9D%9C%8B2&f=false

4.     Any statistical information? Repetition? Data analysis?

5.     Normally, the drying rate curve should be presented as a drying rate versus moisture ratio. Please clarify.

6.     Additionally, the curves are not been processed. For example why drying rate is zero on day 9?

7.     Table 7. Specific energy consumption for solar drying 17.93 kW.h/kg. Are you sure?

The results of current manuscript in part of drying analysis are very raw. The drying curves and not processed. The drying rate curves have a zero point. In current version of the manuscript, I would propose to reconsider after major revision the manuscript. 

Author Response

The authors are thankful to the learned Reviewer for their thoughtful and detailed comments to improve the quality of the manuscript.

Author Response File: Author Response.docx

Reviewer 2 Report

The selected title of the paper does not align with the content of the manuscript. Specifically, it is unclear why the term "IoT" is used in the title when it is not mentioned anywhere else in the manuscript. This discrepancy raises questions about the relevance of IoT technology to the study and may mislead readers about the focus of the research. Clarification or revision of the title is needed to accurately reflect the content of the manuscript.

The abstract lacks detailed explanation of the specific mathematical models used in the simulations. The author should consider providing more information on why the Two-term, Modified Page III, Two-term Exponential, Newton (Lewis), Approximation diffusion or Diffusion Method, and Two-term Exponential models were chosen and how they were compared to other potential models. Additionally, there is no mention of potential limitations or drawbacks of the study that could impact the validity of the results.

While the introduction provides a detailed background on drying techniques and the rationale for exploring solar drying as an alternative, it lacks a clear transition to the specific focus of the study. The mention of mathematical modeling and thin layer drying is somewhat abrupt and could be better integrated into the narrative to provide a smoother flow of information. Furthermore, while the introduction briefly mentions the economic and environmental aspects of dryer technologies, it would benefit from a more explicit statement of the research objectives and hypotheses to guide the reader's understanding of the study's purpose.

It is important to ensure that all abbreviations used in the manuscript are explained at their first occurrence to aid reader comprehension. This practice would enhance the clarity and accessibility of the manuscript, ensuring that readers are able to understand the terminology used without confusion.

The Materials and Methods lacks details regarding the method and specific procedure used to determine the dry matter and moisture content, which are crucial for understanding the drying process. Therefore, it is expected that the authors clearly state the standard method they used for these measurements or provide a detailed description of the method employed. Additionally, there is a lack of information on the process parameters during drying in the "2.3. Experimental Procedure" section, including temperature, airflow, how these parameters were monitored, as well as details on measuring sample mass over time. It needs clarification whether the drying process was interrupted during measurements, the intervals at which measurements were taken, and how relative humidity and temperature were measured. It is also unclear whether these parameters relate to the samples or the drying chamber. Given the shortcomings in the experimental design, questions arise about how accurate modeling of the drying process can be achieved with such an experimental setup. These details are crucial for the transparency and reproducibility of the research and therefore need to be described in more detail. The data processing method and the software used for this purpose are not mentioned anywhere in the manuscript. It is essential to provide information on how the data were processed and analyzed to ensure transparency and reproducibility.

Results and Discussion

·         Moisture Content Analysis: The study presents initial and final moisture content values for different date fruit varieties, highlighting the impact of drying methods on moisture reduction. However, it lacks detailed information on the methodology used for moisture content estimation, including the specific laboratory conditions and procedures followed. Providing such details would enhance the reproducibility and credibility of the results.

·         Drying Rate and Effective Moisture Diffusivity (EMD): The discussion on drying rate and EMD offers valuable insights into the drying behavior of date fruits under different conditions. The comparison between open-air drying (OAD) and solar drying (SD) methods is well-documented. However, the explanation of EMD could be further elaborated to clarify its significance in the drying process and its relation to moisture diffusion mechanisms.

·         Evaluation of Drying Models: The extensive evaluation of drying models provides a comprehensive understanding of the drying kinetics of date fruits. The selection of appropriate models based on statistical measures is justified, but additional insights into the practical implications of model selection would enhance the discussion. Moreover, discussing the limitations or assumptions of the chosen models would add depth to the analysis.

·         Economic and Environmental Analysis: The economic and environmental analyses offer valuable information on the feasibility and sustainability of using solar drying systems for date fruit processing. However, the methodology used for economic evaluation and the assumptions made in the analysis should be clearly outlined to ensure transparency and facilitate comparisons with other studies. Similarly, providing more context on the environmental impact assessment would enhance the interpretation of the results.

The conclusion provides a concise summary of the key findings and emphasizes the importance of understanding drying kinetics for efficient system design. However, the discussion on future research directions could be expanded to include potential areas for improvement or refinement of the study's methodology, as well as the exploration of new applications or extensions of the findings.

Author Response

The authors are thankful to the learned Reviewer for their thoughtful and detailed comments to improve the quality of the manuscript.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors answered my questions in current manner. The manuscript now can be accepted. 

Reviewer 2 Report

The authors have revised and improved the manuscript in response to the reviewers' suggestions.