simulation

This study investigated the effects of common date-storing indicators on the frequency of store pests in six date-producing provinces of Iran in 2022. The research employs an artificial neural network model with three layers: input, hidden, and output. Each layer contains a group of nerve cells which are generally related to all the neurons of other layers, including compliance and non-compliance with the storage index and the unobservable factor resulting from factor analysis. The results showed that the indicators of product layout, including pallets, storage containers, cultivars separation, spacing, and shelving, respectively, have the greatest effect on the severity of O. surinaemensis, E. elutella, E. elutella, E. elutella, and E. calidella. Building indicators, including flooring, internal walls, sloping passage at the entrance, proper access to internal spaces, and the presence of a dock have the greatest effect on the contamination of D. melanogaster, D. melanogaster, E. kuhniella, O. surinaemensis, and E. kuhniella. The indicators of setting the environmental conditions of the warehouse, including ventilation systems, temperature, humidity, environmental hygiene, and warehouse floor, respectively, had the greatest effect on the contamination of E. kuhniella, D. melanogaster, D. melanogaster, E. kuhniella, and D. melanogaster. The neural network model included 28 synapses between different layers. The lighting system, proper access, spacing, and flooring are effectively predict warehouse pests’ population density by 100%, 94.9%, 77.1%, and 60.2%, respectively. These factors are crucial in pest infestations. The algorithm obtained from the neural network determined the importance of complying with storage standards in managing date pests.

This study aimed to combine the response surface methodology and COMSOL simulation to reduce the number of studied treatments, find the effective factors and their interactions and also the prediction model for final dried orange characteristics, and find the shrinkage model of apple fruit concerning the studied drying process factors. A definitive screen design of response surface methodology was designed by Design-Expert software. Factors such as drying time (A: 20-60 ℃), air velocity (B: 0.5-2.5 m/s), sample thickness (C: 3-7 mm), sample diameter (D: 4-6 cm), and drying time (E: 6000-10000s) were investigated. These treatments were simulated in COMSOL software 5.3a. After finding the treatments in Design Expert software, the simulation starts. Results show apple samples results show, that the air temperature and its interaction with other investigated factors, the sample thickness, and the air velocity are effective on the central temperature of the sample. The moisture rate and moisture content are depending on drying time. Apple shrinkage is a logarithmic model as a function of air temperature, sample thickness, and process time. Apple shrinkage during drying significantly affects the thickness of samples. To control the shrinkage rate during apple drying, controlling the time of process and sample thickness is more effective than other processing factors. This leads to a prediction model for drying apples and process control. The optimization is shown the minimum shrinkage is at 0.7mm thickness, 5.45cm diameter, and 9938s process time.

Among the types of heat exchangers, shell and tube heat exchangers are the most common heat exchange equipment. The energy efficiency of a heat exchanger can be increased by improving the heat transfer properties. Nanofluids are a Colloidal suspension of nanoparticles are in a base fluid.The nanoparticles used in nanofluids are usually made of metals, oxides, carbides, or carbon nanotubes. The heat transfer rate is affected by the thermophysical properties of the nanofluid, which increases with the increasing volume of nanoparticles in the base fluid. Nanofluid properties are affected by nanoparticle concentration, purity level, and variable structure. The main purpose of this paper is to provide an overview of the use of nanofluids in shell and tube heat exchangers to increase heat transfer coefficients and simulate the parameters affecting the flow and heat transfer to predict temperature distribution, velocity, and pressure drop in different parts of the heat exchanger.

In this study, Camsol multiphysicas simulation software version 6 was used to build a computational model of shell and tube heat exchanger to simulate temperature, velocity, and pressure drop changes in the heat exchanger. Hot nanofluid (353.15 ° K) enters the tube and water (298.15 ° K) enters the shell. The role of geometry parameters used on heat transfer rate has been investigated and presented. The temperature and total heat transfer characteristics of the pipe wall are calculated and designed for theoretical, experimental, and numerical methods using the K- ɛ heat transfer model.

By performing a computational fluid dynamics study, and calculating the desired values of each of the studied parameters, a good agreement was obtained between the computational fluid dynamics study and experimental results. The results of temperature, velocity, and pressure drop counters show that the addition of nanoparticles to the fluid can effectively increase the thermal conductivity of the fluid the temperature of the added nanoparticles are directly related to the thermal conductivity ratio. The velocity changes in the shell are very small and in most areas of the shell, the speed according to numerical calculations and according to the colored guide bar is about 0.05 meters per second, but at the points of collision of the current with the baffles and inlet and outlet values are different and between 0.15 to 0.2 meters. Is seconds. From the numerical results, it can be seen that the velocity values in the vicinity of the walls are very low, which is due to the strong friction gradient. Examining the temperature-related contours, it can be seen that the heat transfer is not uniform throughout the length of the exchanger and the decrease in temperature in the direction of flow is visible.

The use of alumina nanoparticles in the base fluid by 4% increased the average output temperature by 0.9 degrees in a passing cycle of the system, which increases more and more with the repetition of this cycle. According to the pressure drop contour, the pressure drop of nanofluids is much higher than the base fluid and the pressure drop increases with increasing the concentration of nanofluid.

In the present study, the two-dimensional modelling of heat transfer during the deep-fat frying process was investigated. In the first stage, three temperature levels of 150, 160, and 170 °C were selected for frying and recorded by a K-type thermocouple. In order to record the temperature changes of the sample during the frying process, a three-channel T-thermocouple was placed in the center, on the surface, and between these two points of the sample. In the next step, based on the temperature-to-time diagram, during five periods of frying, the moisture and oil content were measured at all three oil temperatures. As the temperature of the oil increased, both the oil and moisture content of the potatoes decreased. Then, the heat transfer parameter, including the convective heat transfer coefficient, in the range of 83.97578.4 W/m2.K, was calculated and determined. The result showed that the convective heat transfer coefficient is high at high temperatures because of moisture exiting and the high turbulence of the oil flow. This coefficient also has a large influence on frying. The convective heat transfer coefficient was considered the most important parameter in heat transfer modeling, and it was used in software simulation. The geometry of the potato slices was disc-shaped. The mathematical equations of heat transfer were solved using Fourier's law, and the results of solving the equations in modelling were used by COMSOL Multi-Physics software version 5.3.1, and the temperature distribution at the surface and inside the sample was modelled with this software. Finally, the available profiles were represented.

Bread is one of the most important food sources for consumers, especially in developing and underdeveloped countries. Large quantities of bread are wasted every year because different factors affect the number of waste products include flour quality, bread production technology, and the storage condition of the bread. Among the factors affecting the quality of the flatbread, technological factors including the source and method of heating the dough and the type of baking bed are very important. Those factors affect the quality and staleness of the bread and the amount of energy consumed per ton of the produced flatbread. All of these issues depend on how heat and mass are transferred. At present, for the baking of the flatbread, direct heat transfer of the burner (torch) to the dough is utilized in the Iranian bread industry. The use of the direct heat method in baking causes non-uniform heat distribution and non-uniform baking of the flatbread. Also, it causes the deposition of some chemical compounds such as benzopyrenes on the surface of the bread due to incomplete combustion of fuel and gases from the burning process of fossil fuels. At present, the change in the structure of bread production from traditional methods to industrial methods is one of the most important factors in the production of safe and standard bread while improving its quality. The objective of this study was to improve existing systems and developed the new flatbread industrial baking machine to increase product quality and product storability.

The design and construction of the oven were performed based on the existing machine in the bread industry. The final dimension of the bread baking machine was 250 ×250 cm, a height of 160 cm. Rotary bread baking machine with an indirect heating system was designed and heat exchangers of the machine were simulated. The uniformity of airflow velocity inside the exchangers and the distribution of heat on the dough on the baking bed were investigated. After achieving the most effective design, the exchangers were constructed and installed inside the baking machine. A rotary baking bed was constrained with cast iron with a diameter of 220 cm and a thickness of 18 mm that was able to rotate horizontally. A three-phase electric motor with a speed of 1400 rpm and a power of 1.5 kW was used for the rotation system of the bed and carousel assembly. Two heat exchangers with an optimized shape were constructed with SS310 coupled with 2 burners. Bread baking experiments with the developed machine and the existing conventional machines were conducted to evaluate the sensory and staling characteristics of the produced flatbreads from different baking machines.

The simulation results indicated that the air velocity in the center of the middle pipes of the upper exchanger with a standard deviation of 0.05 was in the range of 1.552 to 1.72 ms-1, which means an acceptable uniformity. In the lower heat, there was a relatively uniform air distribution. The experimental validation of the developed simulator indicated that there is good agreement between the measured and predicted air velocity. In the top exchanger, R2 and RMSE were 0.9 and 0.36, respectively and in the top exchanger, they were calculated to be 0.97 and 0.218, respectively. The results indicated that the sensory qualities of the bread produced with the indirect heating system in the present study as well as uniformity of baking and sensory acceptability were superior compared to the bread produced from the conventional industrial machines with direct heating systems (with a total sensory score of 5.09 vs. 4.54). Mold was also observed in a few breads, with direct heating samples, after 168 hours of storage. However, no significant changes were observed in the quality of the bread cooked by direct heating methods after 48 hours of storage, and this type of flatbread lasted more than 168 hours without mold. It should be noted that mold is one of the most important quality deterioration factors and its weight in the quality assessment of the bread is greater than the other quality evaluation factors even though it has not been included directly in the evaluation standards. If the bread becomes moldy, it will be unsafe for consumption and fully wasted. Accordingly, the flatbread produced by the indirect heat was the best choice for long-term storage purposes and the reduction of food waste. Another feature that was evaluated in the bread was the uniformity of baking of all parts of the flatbreads. One of the main problems with the industrial direct heat baking machines is the fact that the outer edges of the flatbread burn due to the inadequacy and somehow incompatibility of the exchangers with the baking space, the dimensions of the flatbread, and incorrect design of the heat exchangers. The flatbread baked with indirect heat and the newly designed exchangers was very uniform with no signs of burning in the outer edges of the bread.

In general, the results of the current study indicated that the use of the simulation tools, the design and manufacturing of the new exchangers and uniform indirect heating of the baking bed resulted in the production of higher quality bread which could be stored for a longer period of time while reducing the food waste. Also, bread prepared using the new machine was free of any contaminants such as PAHs.

In the present study, a convective heat transfer coefficientchanges during deep fat frying was investigated. So, by keeping the oil temperature constant as a heat transfer medium, temperature changes in a potato strip (cube-shaped), in the center and left-right sides of the strip during frying by a three-channel thermocouple was measured. Processing temperature of oil was 150, 160 and 170°C. The strip temperature was recorded by a data logger at     ten-second intervals. Due to no significant changes in the temperature of different selected locations in potato strip, the center temperature was selected and recorded as an effective temperature. Also, heat transfer parameter included convective coefficient () was calculated in the range of 128_515 W/m2.K .Result showed that  is high in high levels temperature because of increasing rate of moisture exiting and turbulence in the oil. Also, with increasing oil temperature, decreasing of oil content and decreasing in moisture content of slices were observed. The mass transfer parameters including the effective moisture diffusivity () and the oil diffusivity () were calculated in the range of 9.12×10-9 _1.31×10-8 m2/s and  1.26×10-5_1.52×10-5 m2/s , respectively. By using the calculated coefficients, heat and mass transfer modeling, was done by mathematical equations and the relevant equations were solved by the method of separation variables. Simulation was also done with COMSOL Multiphysics version 5.3a and the resulted profiles were also presented.

In this research, stepwise cooking and temperature fuzzy controller were designed during the infrared irradiation of apple with intermittent heating method. For this purpose, the dry blanching process and dehydration of apple slices were examined at three temperatures of 70, 75 and 80 °C based on the blanching speed and vitamin C preservation. The fuzzy controller of the temperature with the feedback loop was designed, simulated, and implemented by comparing two first and second order transfer functions in MATLAB software. Simulation efficiency was examined using the indices of integral squared error (ISE), integral absolute error (IAE), integral time-weighted absolute error (ITAE) and steady state error (ess). The results revealed that the temperature of 80 °C and time of 15 minutes were appropriate for blanching operation and temperature of 70 °C was appropriate for dehydration. The simulation results confirmed that the higher order of the transfer function led into a faster response, but increase in oscillations and reduction in the stability were not appropriate.  For the first-order transfer function, the values of efficiency indices, including (ISE), (IAE) and (ITAE) were calculated to be 0.760, 0.821 and 0.589, respectively, of second-order transfer function. The simulation indicated the reliability of the fuzzy control model and showed an acceptable computational efficiency, since the fuzzy rule test during simulation showed a high sensitivity to maintain steady state error (ess) close to zero.

 Garlic "Allium Sativum L." is a relatively perishable product. Approximately 30% of this product is lost annually in the post-harvest stages due to the lack of suitable storage and convenient transportation facilities. It is rich in medicinal and food nutrition and is widely cultivated throughout the world, including Iran. Recently, dried garlic has been used as one of the ingredients and additives of cooked and semi-finished foods such as sauces and soups. Changing the pattern of consumption from the fresh garlic to the dried one has increased the demand for this product. Understanding the moisture and heat transfer mechanism during the drying is crucial to enhance the quality and reduce energy consumption. The quality changes of a dried product are functions of drying condition as like; drying air temperature, drying time, and the warmth of the product surface. By applying higher drying air temperature, shorter drying time and also in parallel with it, slightly lower energy consumption is achievable; however, it will result in higher quality changes. The objective of this study was developing a simulator for drying with variable air temperature to reduce the drying time and lowering energy consumption as well as maintaining the dried product quality at its highest possible level. 

In the present study, the mathematical equations of mass and heat transfer during convection drying of garlic have been developed. The following assumptions were used to develop the mathematical model; 3-D transfer of heat and moisture is accrued; the air distribution is uniform inside the dryer; the distribution of initial moisture and temperature throughout the material is uniform; the product shrinkage is negligible during the drying process; heat transfer to the product through radiation is negligible and conductive heat transfer between trays and product was not included. Third type boundary condition was applied to all air-product interfaces and the equations were solved on three-dimensional geometry of garlic slices simultaneously with the Finite Element Method (FEM) using COMSOL MULTIPHYSICS 3.5 software under different drying air temperature. The temperature and moisture profiles were estimated in a garlic slice by the developed simulator. Mesh independence study was performed to establish an optimal mesh density that gives a solution with acceptable accuracy and four meshes, each containing 1430, 3364, 4362 and 12977 elements were used. The results indicated that mesh independence of numerical solution was obtained when the number of elements was above 4362. The developed simulator was validated by experimental study under different drying temperature conditions; 50, 60 and 70 °C; and different thicknesses of the samples; 2, 3 and 4 mm. At the same time, the engineering and qualitative properties associated with thermal processing of garlic slices were studied, such as the effective moisture diffusivity, apparent density and dry material density, and color changes of the samples. Eventually, by using the simulator, the issue of reducing energy consumption by reducing the total time of the drying along with preserving the apparent quality of the product was examined based on the output data from the simulator through the use of the variable temperature of hot air during the process and in different thicknesses. 

The developed simulator was able to accurately predict changes in the moisture ratio at different temperatures of the hot air and the different thicknesses of the garlic product. The average error in estimating the moisture content at the hot air temperature of 50, 60 and 70 °C was 11%, 6%, and 34%, respectively. Based on the experimental results, the change in hot air temperature and samples thickness did not have a significant effect on the apparent density but affected the final color of garlic slices. The surface temperature of samples had a significant influence on the quality of the dried product; furthermore, the minimum and maximum changes in the color of the samples were observed when the surface temperature of slices was 50°C and 70°C, respectively. The use of drying air at 50 °C and 2 mm thick slices maintains the lightness of the samples and prevents the color changes of the samples during drying. However, the use of hot air at a lower temperature can prolong the drying time. Accordingly, by the developed simulator using the drying air with variable temperature for drying garlic slices was evaluated and the predicted surface temperature of sample was monitored during the drying process with the air temperature of 70°C and by the time that the surface temperature of sample was increased and reached 50°C, the hot air temperature was reduced and the drying process lasted from 30 minutes, with drying air at 50 °C. Despite the use of hot air with variable temperature, no noticeable changes were observed during drying compared to drying with an air temperature of 70 °C and drying time was prolonged only 3 minutes. At the same time, during the 25% of the total drying time the drying air with 20 °C lower than the usual has been used, which will reduce energy consumption. The results showed that by using this method, it is possible to dry the garlic slices in a shorter time. Also, by restricting the temperature rise of the product in the final stages of the process, the color change of the samples is prevented. On the other hand, due to the use of the variable temperature of the drying air, the drying time decreased about 43 minutes as compere with the drying of the sample with the air temperature of 50 °C, which had a significant effect on reducing energy consumption. Similar results were obtained in drying garlic slices with a thickness of 3 mm.
  

 To achieve a high-quality dry product, more transparent color and reduced energy consumption by reducing the drying time, it was necessary to use slices with lower thickness and hot air with variable temperature during the process based on the developed output-model. The proper time to change the air temperature during the drying process was determined. The developed simulator can predict the items mentioned above, with high precision.