High Air Flow Rate Research Articles

Unsteady RANS simulations of laboratory ventilation with chemical spills and gas leakages - Toward balanced safety and energy effectiveness

Laboratories generally set high airflow rates, commonly measured by the number of air change per hour (ACH), to maintain safe ventilation environments in case of unintended chemical spills and gas leakages as well as to remove fugitive emissions. However, unnecessary high ACH results in wastage of energy and at times, even inefficient removal of pollutants. Due to the uncertain impact of ACH, the latest ventilation codes and standards provide laboratories the flexibility to establish performance-based minimum airflow rates instead of adopting standard criteria. As such, with high-performance computing resources, this study applies the Unsteady Reynolds-averaged Navier-Stokes (URANS) simulations to explore the optimal ventilation strategies in a chemistry laboratory with high fume hood density, which is typical in National University of Singapore (NUS) but has not been studied. First, a chemical spill experiment was conducted to validate the simulation methods. Subsequently, transient variations of air contaminant concentration were simulated under chemical spills or gas leakages at 2 to 16 ACH with different fume hood operation during the unoccupied period of the laboratory. The simulation results show that when fume hoods are switched off, increasing ACH makes diminishing decreases of peak concentrations and clearance time of pollutants. In comparison, when fume hoods operate at a minimum airflow rate, mutual interference between room and fume hood exhausts are observed. In this case, increasing ACH becomes less effective for improving the laboratory ventilation. Based on the results, recommendations are given to optimize laboratory ventilation strategies during unoccupied period balancing occupational safety and energy conservation.

Human response to thermal environment and perceived air quality in an office room with individually controlled convective and radiant cooling systems

The purpose of this study is to analyse the human response to the indoor climate with two individually controlled convective and radiant cooling systems: a low velocity unit combined with radiant panel system (LVRP) and a personalized ventilation system combined with a radiant panel system (PVRP). As a reference system without individual control, diffuse ceiling ventilation combined with a radiant panel system (DCV-RP) was also studied. In laboratory conditions, 10 males and 10 females gave subjective response to the indoor climate during various office activities. The results show that with the reference DCV-RP system, the indoor conditions were worse than with the LVRP and PVRP systems. The thermal sensation and perceived air quality with the PVRP system was better than the LVRP system. After a medium activity task, the thermal acceptability reverts faster with the PVRP than LVRP system. Compared with the PVRP system, the subjects preferred the higher airflow rate at the workstation with the LVRP system. Males preferred a higher airflow rate than females under the same conditions with both micro-environment systems. This research found that there was significant variation in the control preferences of the human subjects concerning the micro-environment, and this emphasizes the need for personalized control to ensure that all occupants are satisfied with the indoor conditions.

Combustion and pollutant emission characteristics of argan nut shell (ANS) biomass

This paper presents an experimental study of argan nut shell (ANS) combustion in a lab-scale furnace. Biomass composition, properties and microstructures were determined. Combustion behaviour, fuel burn rate (FBR), pollutants (CO and NOx), modified combustion efficiency (MCE) and ash analysis were investigated. A comparison with wood pellets (WP) complying with the ENplus Standard was performed. The impacts of air flow rate and particle sizes on the combustion characteristics were analysed and discussed using three average ANS particle lengths: 5–8 mm, 10–18 mm and 25–30 mm. The results show that the smallest length of ANS particles induced a higher FBR and a regular distribution of the flame shapes compared to the other sizes and to wood pellets. Furthermore, the combustion temperatures, CO emission and MCE values were improved with the highest air flow rate used. CO emission was strongly affected by the operating conditions while NOx was very low for all selected cases. Elemental ash composition reveals that no ash agglomeration was observed during experiments in terms of alkali index. Moreover, the obtained ash was in the form of powder instead of agglomerated particles. This experimental investigation improves the understanding of the operational characteristics and the combustion effect of ANS biomass.

Optimization of a novel single air-lift sequencing bioreactor for raw piggery wastewater treatment: Nutrients removal and microbial community structure analysis

In this study, a sequencing batch and intermittent air-lift bioreactor (SBIAB) was evaluated under the three independent variables to treat raw piggery wastewater. The effects of hydraulic retention time (HRT), air flow rate and sludge retention time (SRT) on the nutrients removal of SBIAB were researched. The optimum values of HRT, air flow rate and SRT were 8 d, 2 l/min and 20 d, respectively. Meanwhile, the removal rates of chemical oxygen demand (COD), NH4+-N, total nitrogen (TN) and total phosphorus (TP) were up to 89.5%, 93.5%, 61.1% and 57.3%, respectively. Generally, the nutrients removal performance could be enhanced with increasing HRT from 6 to 10 d, while it was inhibited at air flow rate of 3 l/min. Higher air flow rate caused the alkaline pH and high free ammonia concentration, which imposed restrictions on the process of wastewater treatment. In the SBIAB, a coupling of aerobic/anoxic/anaerobic zone was formed according to the changes of oxidation-reduction potential (ORP) values at the optimum condition. Microbial community structure analysis indicated that the functional microbes including Brachymonas, Prokaryote, Giesbergeria, Comamonadaceae bacterium, Clostridiales bacterium, Comamonas, Tissierella, Aequorivita were enriched in the SBIAB, which played a significant role in the removal of complex organics and nitrogen.

Performance improvement of a water-purifying absorption cooler through humidification-dehumidification

An absorption heat pump that achieves water purification and air-conditioning with secondary water purification through humidification-dehumidification is developed. A thermodynamic model of this cycle is formulated and used to predict cycle performance. The cycle with humidification-dehumidification outperforms similar cycles using forward osmosis and membrane distillation at baseline operating conditions by 19% and 12%, respectively, because of the additional evaporator loads imposed by the humidification-dehumidification process. The performance of the cycle is insensitive to ambient temperature and humidity due to the high air flow rate associated with air conditioning. However, cycle performance is sensitive to the water load once the heat transfer fluid flow rates and heat exchanger sizes have been fixed, demonstrating a 12% decrease in performance when the water output ratio is changed from 7% below the baseline to 7% above the baseline. Designs that allow for on-design or below-design operation will allow excellent cycle performance.

Efficient drop reactor processing of methylene blue degradation with silver nanowire catalysts

A drop-based approach to facilitate the remediation of methylene blue (MB) solution via catalytic degradation with silver nanowires on a superhydrophobic substrate with a 2 mm hole without fouling is presented here. Studies on the dynamical response of drop removal via pressure rate perturbation, showed greater elapsed times at the 7.61 μL/s air flowrate with 25 μL and 30 μL volume drops than at higher air flowrates used. These results are accounted for by the rate of air flow through the plastron, used to equilibrate the lowering of pressure in the transparent receptacle that tends to prevent drop dislodgement, being only able to operate up to a specific upper limit. A method that calculates the absorbance values based on the intensity spectrum of the nanowire solution as reference was found to reveal the time progress degradation of MB solution by spectrometry. It showed that a 25 μL drop of the MB solution could be degraded within 15 s using 0.25 mg of the silver nanowire.

On the Ventilation Performance of Low Momentum Confluent Jets Supply Device in a Classroom

The performance of three different confluent jets ventilation (CJV) supply devices was evaluated in a classroom environment concerning thermal comfort, indoor air quality (IAQ) and energy efficiency. The CJV supply devices have the acronyms: high-momentum confluent jets (HMCJ), low-momentum confluent jets (LMCJ) and low-momentum confluent jets modified by varying airflow direction (LMCJ-M). A mixing ventilation (MV) slot jet (SJ) supply device was used as a benchmark. Comparisons were made with identical set-up conditions in five cases with different supply temperatures (TS) (16–18 °C), airflow rates (2.2–6.3 ACH) and heat loads (17–47 W/m2). Performances were evaluated based on DR (draft rating), PMV (predicted mean vote), ACE (air change effectiveness) and heat removal effectiveness (HRE). The results show that CJV had higher HRE and IAQ than MV and LMCJ/LMCJ-M had higher ACE than HMCJ. The main effects of lower Ts were higher velocities, DR (HMCJ particularly) and HRE in the occupied zone as well as lower temperatures and PMV-values. HMCJ and LMCJ produce MV conditions at lower airflow rates (<4.2 ACH) and non-uniform conditions at higher airflow rates. LMCJ-M had 7% higher HRE than the other CJV supply devices and produced non-uniform conditions at lower airflow rates (<3.3 ACH). The non-uniform conditions resulted in LMCJ-M having the highest energy efficiency of all devices.

A computational analysis on the operational behaviour of open-cathode polymer electrolyte membrane fuel cells

In the present work, a comprehensive, three-dimensional computational fuel cell model is developed, validated, and utilized to study the operational and hygrothermal behaviour of an open-cathode (air cooled) polymer electrolyte membrane fuel cell at various ambient conditions compared to conventional liquid cooled cells and a hypothetical isothermal case. The spatial distributions of relative humidity, temperature, and membrane water content are analysed during operation of the cell and the strong hygrothermal characteristic of the open-cathode fuel cell system is established. The high temperature and relative humidity gradients inside the cell are found to limit the cell performance for open-cathode cells unlike the other operational cases. Moderate self-heating followed by membrane drying is found to be the key factor limiting the net cell performance while in operation at moderate-to-high current densities and high air flow rates. The open-cathode fuel cell is also found to perform better at high temperature and high relative humidity ambient conditions; however, in contrast to liquid cooled cells, the performance is restricted by inefficient thermal and water management.

Sterilization effectiveness of in-duct ultraviolet germicidal irradiation system in liquid desiccant and indirect/direct evaporative cooling-assisted 100% outdoor air system

Microorganism contamination in air conditioning systems can cause respiratory diseases in building occupants. This study aims to evaluate and predict the performance of an in-duct ultraviolet germicidal irradiation (ID-UVGI) system to reduce the microorganisms that can grow in the liquid desiccant and indirect/direct evaporative cooling-assisted 100% outdoor air system (LD-IDECOAS). Bacteria and mold on the direct evaporative cooling (DEC) element and in the outdoor and supply air were monitored using a swab and Petrifilm for surfaces and impact sampler for air during the operation of the LD-IDECOAS. Microbial contamination was first verified in the air before performing the sterilization experiment. The experimental results showed that the airborne bacteria were reduced by 78.3% after the operation of the ID-UVGI system but there was almost no reduction in the airborne mold. The bacteria and mold concentration on the DEC surface were decreased by 99.7% and 96.7% respectively 3 h after the ID-UVGI operation. Even after the ID-UVGI system was operated for 6 days, the microbial contamination in the downstream water was not decreased significantly; the inside of the DEC element was suspected to be improperly sterilized. The operating times of the ID-UVGI system needed to inactivate the microorganisms were predicted from the UV–C intensity distribution by irradiation analysis. Legionella sp. and Penicillium sp. were predicted to be inactivated by 99.9% with UV–C exposures of 6 s and 15 min 57 s or less respectively when the LD-IDECOAS is operated at the highest air flow rate.

Removal of Tetracycline from Wastewater Using Circulating Fluidized Bed

In this study, the circulating fluidized bed was used to remove the Tetracycline from wastewater utilizing a pistachio shell coated with ZnO nanoparticles. Several parameters including, Tetracycline solution flowrate, initial static bed height, Tetracycline initial concentration and airflow rate were systematically examined to show their effect on the breakthrough curve and the required time to reach the adsorption capacity and thus draw the fully saturated curve of the adsorbent. Results showed that using ZnO nanoparticles will increase the adsorbent surface area and pores and as a result the adsorption increased, also the required time for adsorbent saturation increased and thus the removal efficiency may be achieved at minimum antibiotic flowrate, maximum bed height, higher antibiotic concentration, and higher airflow rate. Also, a minimum fluidization velocity correlation was developed in this study. This correlation was found to be a function of liquid velocity, bed height, particle size, and particle density. The results showed that circulating fluidized bed has a better performance and last more than two hours before the bed biomass exhausted in comparison with traditional fluidized bed.

Evaluating the effect of air flow rate on hybrid and conventional membrane bioreactors: Implications on performance, microbial activity and membrane fouling

This study addressed the impact of air flow rate on the performance, membrane fouling behaviour and microbial community of a sequencing batch conventional membrane bioreactor (SB-MBR) and a sequencing batch hybrid membrane bioreactor (SB-HMBR) with carrier media for biofilm growth. Two different scenarios were evaluated: high (6.4 L min−1) and low (1.6 L min−1) air flow rates, associated with high (4.5 mg L−1) and low (1.5 mg L−1) dissolved oxygen (DO) concentrations and specific aeration demand per membrane area (SADm) of 0.426 and 0.106 m3 m−2 h−1, respectively. Both reactors were subjected to alternating non-aerated and aerated conditions for organic matter (as chemical oxygen demand - COD), nitrogen and phosphate removal from a municipal wastewater. From the bacterial community analysis, the key players in nutrient removal processes were assessed. The results showed that COD removal efficiencies were above 95% in both MBRs, regardless of the aeration intensity, while complete ammonium removal was observed at the higher DO. However, nitrifying activity was adversely affected under low DO levels. High nitrification levels were re-established faster in the hybrid MBR, thanks to the presence of biofilm, where nitrifying activity was favoured and the bacterial community profile did not exhibit substantial changes upon DO reduction. A higher denitrification potential was found for the carrier-based MBR, resulting in lower effluent nitrate concentrations. Regarding phosphorus removal, a slight improvement was observed in the SB-HMBR at reduced DO, while in the SB-MBR it remained practically constant. Moreover, the specific phosphate uptake rate exhibited a significant increase, especially in the hybrid MBR, reaching 44.6 mgP gVSS−1 h−1. At lower aeration rate, however, worse filterability and higher membrane fouling rates were observed, especially in the conventional MBR. Overall, the results demonstrated that the hybrid MBR better withstood the reduced air flow rate and DO as compared to the conventional counterpart.

Air Flow Model for Mixed-Mode and Indirect-Mode Natural Convection Solar Drying of Maize

An air flow model for mixed-mode and indirect-mode natural convection solar drying of maize to help understand the factors that influence air flow in the dryer is presented. Temperatures at various sections of the dryer obtained from drying experiments were input to the air flow model to predict the respective thermal buoyancies. The air flow rate was determined by balancing the sum of the buoyancy pressures with the sum of the flow resistances in the various sections of the dryer. To validate the model, the predicted air flow was compared with measured air flow from experiments. For both the mixed-mode and indirect-mode, the biggest driver of the air flow is the thermal buoyancy created in the collector, while the grain bed is the dominant pressure drop. Thermal buoyancy on top of the grain bed is largely responsible for the variation in air flow, translating into low mass air flow during the early stages of drying when grain moisture is high, and higher air flow in the later stages when grain moisture is low. The heating of the grain bed by direct radiation in the mixed-mode translates into a slightly higher air flow rate than the indirect-mode. The implications are that a thinner grain bed results in shorter drying time as it has a higher air flow rate than a thicker one. To mitigate the low air flow at the early stages of drying, the collector length should be appropriately designed for a desired air flow.

Chars from wood gasification for removing H2S from biogas

Biomass gasification is a mature thermochemical process used to produce a gaseous fuel to run burners, engines, and gas turbines. One of the byproducts of biomass gasification is char, which is a residue with low value and sometimes this material is even considered waste. Therefore, options for using gasification chars are required. On the other hand, there is a necessity of making biogas production and use more attractive by employing cheap materials for the biogas cleaning process. One of the promising options for using gasification chars is for cleaning biogas produced via anaerobic digestion (AD). The objective of this work was to assess the use of residual gasification chars from fast growing wood species (Eucalyptus Grandis-EG and Pinus Patula-PP) to remove hydrogen sulfide (H2S) from biogas produced via AD. Gasification chars were produced employing a laboratory scale downdraft gasifier. EG char (EG-C30) was produced by gasification of EG using a 30 L min−1 airflow, whereas the PP chars (PP–C20 and PP-C40) were produced from PP using 20 and 40 L min−1 airflow. Results show that these three chars offer potential for biogas cleaning, although PP-derived chars produced at higher airflow rates are more effective. The H2S removal capacity of the chars is ascribed to their large apparent surface area (up to 517 m2 g−1) and the presence of minerals and metals (e.g., Ca, K, and Fe) in the chars’ ash.

Can microaeration boost the biotransformation of parabens in high-rate anaerobic systems?

The main objective of the present study was to demonstrate microaeration as an effective strategy to boost the biotransformation of four parabens (methylparaben, ethylparaben, propylparaben, and butylparaben) in an upflow anaerobic sludge blanket reactor operated at a short hydraulic retention time (8 h). Moreover, the effect of different airflow rates (1−4 mL min−1) was also assessed from an engineering and microbiological perspective. Low mean removal efficiencies (REs) (14–20 %) were achieved under anaerobic conditions. However, the addition of only 1mL air min−1 (0.027L O2L−1 feed) remarkably boosted the biotransformation of parabens, ensuring mean REs above 85 % for all compounds. In contrast, the increase in the airflow rate had a minor impact on the process, and an apparent saturation in the removal capacity was observed, noticeably from 2 to 4 mL air min−1. The reactor presented high stability throughout the experiment, and microaeration did not impair the organic matter removal and methanogenesis. However, high airflow rates can dilute biogas, compromising its use as a fuel in combined heat and power units. The microaerobic conditions increased both richness and diversity of the reactor’s microbiota, likely favoring the growth of oxygenase-producing microorganisms, which may have played a role in the biotransformation of parabens. Finally, the high REs of parabens reached in the microaerated reactor, a more cost-effective technology, are comparable to those found in high-cost wastewater treatment systems, such as activated sludge and its variants.

Simulation Studies of Numerical Relationship of Sewage Energy Dissipation Chamber Efficiency

The paper introduces a computer model to simulate design of an energy dissipation chamber (EDC). This model allows expressing the air flow rate through the system as a function of the incoming effluent rate. A method is developed to proceed with statistical analysis of simulation results. A set of plots of air flow rate is developed for effluent rates under different parameters of energy dissipation chamber. The approximating function and coefficients allowing obtaining the air consumption under certain conditions (geometrical parameters of the energy dissipation chamber and the effluent rate) are represented. The graphs are obtained in the form of three-dimensional surfaces reflecting a dependence of the ejected air flow rate on the incoming sewage liquid rate for at various values of the stand pipe embedment relative to the liquid level. The developed graphs show that the highest air flow rate is achieved at the maximum water flow rate and at the minimum embedment. Thus, the numerical dependences of the ejected air flow rates were obtained for the energy dissipation chamber as functions of the water flow rate. The embedment of the stand pipe at the level of the overflow wall and the zero inlet radius are shown to be the most effective parameters of energy dissipation chamber design.

Experimental observation of oil mist penetration ability in minimum quantity lubrication (MQL) spray

Minimum quantity lubrication (MQL) is an eco-friendly cooling and lubricating method that has its importance in machining sustainability. However, the behavior of the MQL droplets remains questionable. The present study is conducted to investigate the penetration performance of MQL with different combination of spray parameters and capillary sizes. An observation platform has been designed, which makes the overall penetration process controllable. The results have shown that the shortest penetration time was obtained with larger capillary size, higher air flow rate and the corresponding smaller droplet size. However, the increase of air flow rate has the optimal value when the objective is to penetrate to 1 mm deep from the entrance, whereas it has not shown the similar regulation when the droplet flowed deeper to the center due to the long transport distance has amplified the effects of multiple influence factors. The observation results were verified through simulation and cutting experiment.

Sıkma Kuvveti Uygulamadan Değişken Şekilli Yumuşak Dokuların Kavranması İçin Yeni Bir Laparoskopik Tutucu Tasarımı ve Uygulanabilirlik Testleri

Cerrahlar, Laparoskopik cerrahi sırasında yumuşak dokuları tutmak ve hareket ettirmek için tutucular kullanmaktadır. Bu tutucuların kavrama çeneleri, dokuların kaymaması için değişik yapılarda dişli yapıyasahiptirler. Dokuların tutucu çeneler arasında sıkıştırılması sonucunda doku hasarı riski oluşmaktadır. Bu çalışmada bu riskin ortadan kaldırılması için Bernoulli prensibi kullanılarak çalışan, dokuları sıkmadankaldırabilen yeni bir Laparoskopik tutucu tasarlanıp üretilerek deneysel çalışma ile uygulanabilirlik testleri yapılmıştır. Tutucu, doku ile arasında Bernoulli prensibi ile yüksek hava akış hızı ile vakum oluşturularakçalışmaktadır. Kaldırılan dokuların kuvvetli hava jetinden zarar görmemesi için eksenel yönde akan havanın akış yönünü değiştirmek amacıyla tutucu yüzey merkezine deflektör yerleştirilmiştir. Çalışma, Bernoulli prensibi ile çalışan bir tutucunun yumuşak ve esnek dokuların sıkıştırılmadan kaldırılması ve hareketi için uygulanabileceğini göstermiştir.

Testing of a novel convex-type solar absorber drying chamber in dehumidification process of municipal sewage sludge

Each day high portion of municipal wastewater sludge is generated in cities and developing a suitable and environmentally friendly treatment technique for municipal wastewater is required. Providing a cost-effective and suitable way for sewage sludge refinement with the purpose of reducing environmental impacts or reutilization of sewage sludge can be an important issue for researchers. In the present study, a novel convex-type solar absorber assisted dryer has been designed for drying municipal sewage sludge. In the experimental setup, an unglazed single-pass solar air collector has been used as main air heater and integrated to the drying conventional and modified drying chambers. Experimental and CFD simulation have been used to investigate the performance of fabricated solar energy assisted dryers. Also, the effectiveness of the developed system has been analyzed in various conditions to clarify the potential of fabricated dryers. According to the results utilizing convex solar absorber led to provide high air flow rate with high temperature inside the drying chamber and consequently shortened the drying time. Experimentally obtained average energy efficiency of the modified and conventional indirect solar drying system were in the range of 32.85–47.09% and 21.32–30.45%, respectively. Moreover, the experimental results collected from CSD (conventional solar dryer) and CSASD (solar dryer with convex solar absorber) are also discussed in terms of R2, RMSE, RRMSE, MBE, and MAPE, and a very satisfying correlation between the systems CSD and CSASD is noticed with the statistical metrics. The findings of the present study demonstrate the potential of utilizing the designed dryers in drying municipal wastewater sludge.

Experimental Study of Liquid Spray Mode of Twin Fluid Atomizer Using Optical Diagnostic Tool

Twin fluid atomizers allow for two different spray forming modes, flow focusing and flow blurring, depending on the operating, geometric, and thermophysical properties of the working liquids. In flow focusing mode, the liquid jet breaks outside the injector, whereas in flow blurring mode, the liquid jet breaks inside the atomizer. Operating conditions are believed to play an essential role in determining the size and velocity of droplets with specific geometric and fluid properties. This work investigates the effect of air flow rate and liquid flow rate on spray characteristics by varying them independently. The geometric parameters, height (H = 0.3 mm) and orifice diameter (D = 1.5 mm) of the atomizer are kept constant (with H/D = 0.2). Spray mode is identified using high-speed images. Phase Doppler particle analyzer is used to measure droplet size and velocity simultaneously. Regardless of liquid flow rate, flow focusing mode is observed at low air flow rate and flow blurring mode is observed at high air flow rate. In general, flow blurring mode produced smaller droplets at higher velocities than flow focusing mode. The Joint probability distribution function of droplet size and velocity shows unimodal near the exit of the atomizer and bimodal distribution around 50 mm downstream due to the completion of the secondary breakup around that position and the subsequent loss of momentum due to the resistance of the surrounding air from the injector outlet. Flow focusing mode showed that sauter mean diameter and mass median diameter tend to increase initially due to coalescence of the spray and begin to decrease due to secondary breakup. The joint probability distribution of droplet Weber number and the droplet Reynolds number indicate that the flow blurring spray produced finer and faster droplets than the flow focusing spray. Overlapping of two Gaussians representing smaller and larger droplets best fits the droplet probability distribution as compared to lognormal or gamma or beta distribution.

Exploration of heat and momentum transfer in turbulent mode during the precooling process of fruit.

Developing a simulator is a prevalent method for the study of any process in which various phenomena occur simultaneously, such as the precooling process; it is also necessary in package designing. During the precooling process of fruit and in the case of large packages at high airflow rates, the flow regime inside the packages is turbulent, which is in most studies assumed to be a laminar flow that causes low prediction accuracy. In the present study, a mathematical model consisting of heat and momentum transfer in the case of a transient and a k‐ɛ turbulence model, respectively, was developed in the precooling process of fruits. Two packages and two airflow rates were used to validate the model. The results demonstrate that the turbulence‐model‐based simulation of the precooling was carried out with a lower element number, within a shorter time, and with a satisfactory accuracy (R 2 > .93866 & RMSE < 0.62). The model could predict the air movement between the fruit and consequently the heat transfer between the air and fruit. The simulator could be utilized to package designing and predicting the precooling time at the industrial scale to prevent the over‐cooling of fruits and reduce energy consumption. Based on the results, the precooling of apples in the commercial package was conducted in both experimental and simulation methods with high heterogeneity lasting 268 and 520 min at airflow rates of 0.5 and 1.5 L s−1 kg−1 p, respectively. By using the developed simulator, the new package was designed for apple through which the cooling time and heterogeneity decreased 48% and 35%, respectively, as compared with those obtained in the commercial package.