Cold Storage Chamber Research Articles

Development and characterization of sandwich panels for thermal insulation in a cold storage chamber

Sandwich composites are materials that have superior properties including low weight, high impact energy absorption and high thermal insulation features, compared to conventional materials. In this study, four different sandwich samples were explored for use in cold storage chambers. The composites were created using an injection molding process with polyurethane foam as the core and different materials (glass fiber reinforced polyester, galvanized steel, aluminum sheets and crimped aluminum) as face materials. Morphological, physical and mechanical properties were evaluated. An inexpensive and nondestructive method was used to determine the thermal behavior of the sandwich panels, and the surface temperature evolution was thermally monitored during the tests. In general, results showed that polyurethane had a homogeneous distribution of size and shape with closed cells, which can improve the retention of the insulating gas. Additionally, the compressive strength of polyurethane within the composites exhibited typical values to be used in specific applications. Thus, the sandwich with galvanized steel exhibited lower flexural strength, which provides more freedom in panel design. The overall heat transfer coefficient of the panels in the form of cubes presented values below the maximum limit requested by ABNT NBR-15457. Finally, the composite galvanized steel/polyurethane/galvanized steel achieved the best performance for use as a thermal insulation material in a cold storage chamber.

The influence of gamma irradiation on the storability and biochemical parameters of potato tubers

Potato storage is a complex technological process aimed at reducing weight losses and maintaining the biochemical and consumer indicators of tubers at an appropriate level. Depending on the storage temperature, the amount of losses on sprouts in the overall structure of waste can be a significant. Currently, in most European countries, the use of a classic potato tuber germination inhibitor based on the active ingredient chlorprofam is prohibited for environmental reasons. In this regard, an alternative method of restraining the germination of ware and intended for industrial processing potatoes based on the use of gamma irradiation is of interest. Studies on gamma irradiation of tubers using 60Co were conducted in 2019-2021 at the Russian Institute of Radiology and Agroecology (Obninsk), followed by storage of potatoes in cold storage chambers of the Russian Potato Research Centre at two temperatures - 6-7 °C and 9-10 °C. The studied radiation doses were 15, 25 and 50 Gy. It was found that potato weight losses during storage depended mainly on temperature (influence of factor 42.2%) and gamma irradiation (influence of factor 42.2%). For ware potatoes (6-7 °C), gamma irradiation doses of 15 and 25 Gy were optimal; for potatoes intended for processing into fried products (9-10 °C), - 50 Gy. Irradiation at these doses significantly reduced the germination of tubers and the amount of total losses during storage. At a storage temperature of 9-10 °C and irradiation dose of 50 Gy, there was also noticed a decrease in reducing sugars content in tubers by 2-2.5 times, which made it possible to obtain the final product when frying of higher quality in terms of color. There was no significant effect on the content of dry matter, starch, nitrates and vitamin C in tubers. After irradiation doses of 25 and 50 Gy a slight decrease in protein content was noticed.

Image-Analysis-Based Approach for Identification of Air Cooler Heat Transfer Degradation during Frosting Process

Fin-and-tube heat exchangers have been extensively used in many fields, especially in heat, ventilation, air-conditioning, and refrigeration systems. In the case of the operation of a fin-and-tube heat exchanger as an air cooler, frost formation is an important effect that should be taken into account. The frost accumulation process is undesirable since it deteriorates heat transfer due to the insulation of the frost layer as well as causing excessive pressure loss. The analysis of the effect of the frosting process on a fin-and-tube air cooler performance is presented in this paper. Based on long-term experimental investigations applied to the air cooler in a cold storage chamber, the general degradation of the heat exchanger performance is discussed. The influence of frost on the cooling capacity, by-pass factor, and thermal resistance is analysed. The temperature distribution of the air passing through the air cooler before and after the defrosting process is presented and discussed. A method for the assessment of the amount of frost formed at the air cooler surface, based on visualisation of the air cooler during operation and synchronised with the thermal measurements, is developed. The results show that the frosting process causes deterioration of the cooling capacity by up to 40% in the analysed case. Correlation is demonstrated between frost formation and heat transfer degradation in the air cooler.

Evaluation of the results of temperature mapping of warehouses

Mapping of cold storage chambers is carried out for optimal operation of the microclimate monitoring system in pharmaceutical warehouses, especially when it comes to the storage of medicines, preparations of biological origin, medical products. A number of medical materials remain active only when a controlled temperature regime is organized in the storage place. Therefore, the control of climatic conditions is a prerequisite.

Intermittent temperatures in the conservation of ‘BRS Kampai’ peaches

This study aimed at evaluating the quality of peaches borne by the cultivar BRS Kampai when cooled at intermittent temperatures throughout storage. They were stored at 1°C and relative humidity between 80% and 90% in a cold storage chamber. The following treatments were applied: T1 - fruit stored at 1±0.5°C; T2 - fruit stored at 1±0.5°C and increase in temperature every five days to 25°C; and T3 - fruit stored at 1±0.5°C and increase in temperature every seven days to 25°C. Fruit were submitted to increase in temperature when they were withdrawn from the cold storage chamber and kept in a heated room. Evaluations were conducted when fruit were harvested, after 10 cold storage days and 2 days of commercialization simulation at 25ºC (10+2) and after 20 cold storage days and 2 days of commercialization simulation at 25ºC (20+2). Peaches were evaluated in terms of mass loss, pulp firmness, soluble solids, titratable acidity, pH and epidermis color. T1 exhibited higher mass loss, higher soluble solid content and higher pulp firmness after 20 cold storage days, by comparison with the other treatments. T2 led to lower mass loss after 20 cold storage days than the ones of the other treatments. However, T2 also showed higher loss of pulp firmness in the same period. The use of intermittent temperatures throughout storage of ‘BRS Kampai’ peaches may be an alternative to extend their post-harvest period.

Impact of Postharvest Handling on Preharvest Latent Infections Caused by Monilinia spp. in Nectarines.

Latent infections caused by Monilinia spp. in nectarines cause great economic losses since they are not detected and rejected at harvest and can appear at any time post-harvest, even at the consumer’s home. The effect of a pre-cooling chamber, water dump operation, and cold-storage chamber on the activation and/or development of preharvest latent infections caused by Monilinia spp. on nectarines were studied under different postharvest conditions: (a) cold storage for 0, 1, or 3 d at 4 °C at either 75% relative humidity (RH) or 100% RH before water dumping, (b) water dumping for 10 minutes at 15 °C, and (c) cold storage for 0, 3, or 10 d at 4 °C at either 75% RH or 100% RH after water dumping. These storage conditions were transformed to fungal physiological time. For visualization of the latent infections caused by Monilinia spp., the nectarines were placed in sterile paper bags and frozen at −20 °C for 48 h in order to damage the epidermis. To compare different handling scenarios, the incidence of latent infection was modelled for physiological time description by a modified Gompertz model. The activation and/or development of preharvest natural latent infections caused by Monilinia spp. at postharvest was mainly related to temperature and incubation time at postharvest. Storing nectarines with any postharvest handling less than 11 days at 4 °C avoids brown rot symptoms and reduced the activation and/or development of pre-harvest latent infections caused by Monilinia spp., while more cold days caused the exponential phase of latent infection activation and/or development. The Gompertz model employed could be used for predicting the activation and/or development of latent infection caused by Monilinia spp. at postharvest conditions and looks at the postharvest life. To our knowledge, this is the first time that the effects of post-harvest handling on latent infections in fruit have been studied.

Design of a low cost, smart and stand-alone PV cold storage system using a domestic split air conditioner

To reduce post-harvest losses of food produce and ensure a better return to marginal farmers, a small cold storage has been developed using a domestic split air conditioner. The developed solar-powered cold storage is a low cost, simple and energy-efficient unit. Installation, operation and maintenance costs of the cold storage are also less. The cold storage is integrated with IoT-based sensors for remote monitoring and controlling of temperature and humidity as well as tracking of the stored items. It uses multiple sensors and a microcontroller to maintain and monitor the desired temperature and relative humidity. Average recorded temperature and relative humidity of the cold storage chamber is found to be 6.88 (±0.7) °C and 95 (±1) % respectively. Total cost of the designed 10 t capacity cold storage is around $ 15710 in India including installation charges. This low-cost cold storage can be owned by a group of farmers in the same locality for using it on a sharing basis or it can be owned by a produce trader to store a variety of fruits and vegetables. Using the developed cold storage, total savings to farmers is calculated to be $ 7449 per year. Farmers or traders can save around $ 20.46 in storage rent per tonne per week considering an average 70% utilization of 10 t capacity of the cold storage throughout the year. Further, the cost of cold storage can be recouped from the rent benefits within the first 2.1 year period.

Cladosporium species causing “Cladosporium rot” on “Bosc” pear fruit in Argentina

“Cladosporium rot” on “Bosc” pear fruit during cold storage causes significant economic losses and has been reported in recent years in the productive valleys of Río Negro and Neuquén. The species involved were not determined. During 2016-2017, “Bosc” pears (Pyrus communis) in cold storage chambers exhibited external brownish black circular spots caused by Cladosporium spp. The objective of this work was to determine the Cladosporium species that caused the above mentioned symptoms. The morphological and molecular analyses of the partial sequence of the actin gene (ACT) supported the identification. Cladosporium macrocarpum, Cladosporium subtilissimum and Cladosporium floccosum were determined as the species involved in the disease. Although Cladosporium has been reported to cause pear rot, this is the first report to identify these species as causal agents of this fruit disease.

Temperature simulation and control in refrigerated storage chambers for fruit

Fruits such as guava or grapes need to be stored for long times under refrigerated conditions, in order to prevent decay. Therefore, it is important to count on a refrigerated storage chamber with controlled temperatures, as required by every stored fruit. The temperature in the refrigeration system’s steam-compression evaporator will be limited by the temperature required by the cold storage chamber. The purpose of this research was to develop a program for temperature simulation and control for refrigerated storage chambers for fruit. The programming research was carried out at the Informatics Laboratory of the Agroindustrial Engineering school of the Universidad Nacional de Moquegua, Peru. The temperature simulation and control program for refrigerated storage chambers for fruit was developed with National Instruments’ LabVIEW programming language, 2016 version. The simulation and modeling programming block diagram and front panel were developed for temperature control in such storage chamber, which will allow the evaporator’s operation when the temperature sensor shows temperatures above the set point and deactivation when the temperature is below the set point, in order to keep the temperature required for conservation of the fruits stored.

Cold thermal energy storage with lauryl alcohol and cetyl alcohol eutectic mixture: Thermophysical studies and experimental investigation

Abstract The surging demand for thermal energy storage (TES) directs considerable attention towards the development of phase change materials (PCMs). This study has the objective to develop a eutectic PCM for effective cold thermal energy storage. The work involves preparation, thermophysical property analysis and experimental studies of a novel binary eutectic mixture. The technique of Differential Scanning Calorimetry is used in determination of thermophysical properties of the prepared eutectic. Results show that the 80:20 eutectic composition of lauryl alcohol and cetyl alcohol with melting temperature of 20.01 °C and latent heat of 191.63 J g−1 is fit for use in cold thermal energy storage. The material also proves to have good thermal conductivity. Thermal stability and reliability studies which are carried out using accelerated thermal cycling tests and thermo gravimetric analysis provide positive reports for the new mixture. An experimental investigation on the effectiveness of the identified PCM is carried out by using it in a cold storage chamber. Experimental studies report a solid improvement in cold energy containment of the PCM incorporated storage chamber resulting in considerable energy savings.

Seed germination of pitaya (Hylocereus spp.) as affected by seed extraction method, storage, germination conditions, germination assessment approach and water potential

ABSTRACTTo breed and preserve pitaya (Hylocereus spp.) genetic resources, reliable information on seed storage and germination conditions is needed. Therefore, this study was undertaken to evaluate the effects of the following factors on germination of pitaya seeds: seed extraction method (manual vs. enzymatic seed extraction), storage time and conditions (up to 12 months at room temperature and in a cold storage chamber), germination conditions [temperature (15, 20, 25 and 30ºC) and light (blue, red and darkness)], germination assessment method (conventional vs. automated with digital image analysis), harvesting season (2014 and 2015), and water potential (−0.5, −1.0 and −2.0 MPa induced by polyethylene glycol 6000 or NaCl). Results showed that freshly extracted seeds germinated close to 100% within one week. Enzymatic seed extraction increased germination speed. Room temperature-stored seeds lost viability compared to cold-stored seeds, whose germination did not change across 12 months of storage. When seeds were germinated at 15°C and in darkness, germination rate and speed decreased. Conventional and image analysis approaches showed a high coefficient of determination when measuring seed germination and allowed to calculate additional parameters, such as maximum germination (gMAX) and time to achieve 50% germination (T50). Water potential of −0.5 MPa negatively affected seed vigor but not gMAX; germination was inhibited below −1.0 MPa. Hylocereus seeds were more affected by polyethylene glycol 6000 than by NaCl at the same water potential.

Numerical modelling of air-cooler using simplified methods

The fin-and-tube air coolers have been extensively used in refrigeration systems applied to cold storage chambers. The performance of the heat exchanger affects the efficiency of the systems and makes the study of heat exchanger becomes important. Prediction of the temperature, humidity, as well as velocity distribution in cold storage chamber requires accurate prediction of operation of the finned air cooler. The presence of the air cooler unit is usually taken into account by the investigators, but with very simplified geometry and physics. Results of numerical modelling using the computational fluid dynamics (CFD) software ANSYS FLUENT of fin-and-tube air cooler is presented in the paper. Two different approaches were used: the Dual Cell Model and porous media model.

Calculation of Seebeck Coefficients for Advanced Heat Transfer Modules

Advanced thermal control technologies have been required for power generation method and electric/hybrid vehicles. In the power devices, a high density of electric power within the small size (a few mm2) and their small heat capacity raise the temperature instantaneously. However, because hybrid vehicles have a limited space for an equipment of electric power conversion systems, the electrical modules for them should be as small as possible. This trend would continue to demand smaller size of power devices in near future. Therefore, it is required to provide faster response of cooling systems. One of the methods to realize this is Peltier cooling. The conventional Peltier devices are mainly applied to such as cold storage chambers. Because the function of the conventional device makes something a lower temperature than that of neighboring ambient, it is generally concluded that the thermal conductivity of the Peltier devices should be low. In contrast, in order to suppress the increase of the temperature of the power devices, Peltier devices should have a high thermal conductivity. Thus, we focused on silicon (Si), which thermal conductivity and Seebeck coefficient are high, as a material of the Peltier devices. The calculated power factor of Peltier effect (σS 2) of Si has a maximum when the carrier density is within 1018- 1019 cm-3. With such a carrier concentration of bulk Si, a contact resistance between Si and electrode metal may be not negligible. Therefore, it is necessary to apply the technologies for decreasing the contact resistance, such as higher carrier doping or metal-silicidation. Moreover, an application of Si-based Peltier devices for power devices requires optimizations of the structure of cooling system by predicting the cooling performance. Specifically, it is necessary to calculate the Seebeck coefficient, resistivity, and thermal conductivity of the Si-based Peltier devices with layered structures. In fact, some of reports have discussed the dependencies of electrode metals on these properties of Si. However, there are few reports on quantitative evaluation about the mechanism or the mechanism of electrode dependence of the Seebeck coefficient. Therefore, in this research, we calculated the Seebeck coefficient by using 3D model, and investigated the effect of interface layer between metal and Si. The structure of the Si sample for the calculation is the following: two electrodes with 2.0 mm × 0 .5 mm were deposited on the both ends of the Si substrate with the size of 2.0 mm × 15.0 mm × 0.625 mmt. It was assumed that the interface layer is formed between these electrodes and Si substrate. In addition, we investigated the influences of the Seebeck coefficient, resistivity, and thermal conductivity of the interface layer on the total Seebeck coefficient of the whole system. This total Seebeck coefficient was calculated by measuring potential difference ΔV between the two electrodes of a sample with a temperature difference ΔTof 50 K. These calculations revealed that resistivity of the interface layer do not affect the total Seebeck coefficient. On the other hand, our experimental results showed that the total Seebeck coefficient depended on the composition of electrodes (a silicide or metal) on Si. In order to explain this discrepancy, other factors which dominate the Seebeck coefficient, such as a work function of electrodes, would be taken into account. This research is supported by “Thermal Management Materials and Technology Research Association (TherMAT)” in New Energy and Industrial Technology Development Organization of Japan. Figure 1

Numerical Modeling of Fin Heat Exchanger in Application to Cold Storage

ABSTRACTThe fin-and-tube heat exchanger are extensively used in refrigeration systems applied to cold storage. The performance of the heat exchanger affects the efficiency of the refrigeration system. Prediction of temperature, humidity, as well as velocity distribution in a cold storage chamber requires accurate prediction of operation of the finned air cooler. The operation of the air cooler unit is usually taken into account in modeling of operation of the cold storage chambers, but with very simplified geometry and physics. On the other hand numerical investigations of the heat exchangers are focused on thermal performance mostly in order to improve the overall heat transfer coefficient or to optimize its geometry. Results of numerical modeling using the computational fluid dynamics software ANSYS FLUENT of fin-and-tube air cooler applied on a cold storage chamber is presented in the paper. Two different approaches were used: the dual cell model, and porous media conditions. Numerical predictions of air temperature as well as air velocity at the air cooler outlet were also validated on the basis of the own experimental data.

Measurement Approach of Mean Heat Transfer Coefficient for Packed Bed of Vegetables

Abstract The non-invasive measurement approach of the mean heat transfer coefficient for the packed bed of vegetables may be thought as still open issue. There is a clear need for the assessment of heat transfer conditions for various types of fruits and vegetables in order to accurately predict the thermal load that is necessary to select refrigeration equipment for cold storage chamber. Additionally, there is significant development in numerical modelling of heat and mass transfer processes in cold storage chambers for fruits and vegetables which requires precise heat transfer prediction. The theoretical basis for the indirect measurement approach of mean heat transfer coefficient for the packed bed of vegetables that is based on single blow technique is presented and discussed in the paper. The approach based on the modified model of Liang and Yang was presented and discussed. The testing stand consisted of a dedicated experimental tunnel along with auxiliary equipment and measurement system are presented. The geometry of the tested vegetables bed were presented. Selected experimental results of heat transfer are presented and discussed for the packed bed of carrots. These results were presented as dimensionless relationship. The obtained results were compared with the existing dimensionless relationships developed for the packed bed consisting of elements of various regular shapes.

Numerical simulations of fin and tube air cooler and heat and mass transfer in cold storage

Fin-and-tube heat exchangers are extensively used in refrigeration systems applied to cold storage. Performance of the heat exchangers strongly affects the efficiency of refrigeration systems. Prediction of temperature, humidity, as well as velocity distribution in cold storage chamber requires accurate prediction of the finned air cooler operation. The operation of the air cooler unit is usually taken into account in modelling of the cold storage chamber but with very simplified geometry and physics. Results of numerical modelling of cold storage chamber equipped with the fin-and-tube air cooler are presented in the paper. Porous media conditions were applied for modelling of the analysed heat exchanger. The numerical results were evaluated on the basis of the experimental data. Good agreement between numerical and experimental results was achieved.

Solar PV powered on-farm cold storage design software HimSaurya for improving storage quality and reducing wastage of perishable agricultural produce

Cold-chain management in India has been accelerated in last decades to reduce postharvest losses. However, most of the tropical and sub-tropical agricultural as well as horticultural produce goes in waste due to its perishable nature and improper cold chain management on-farm. Thus, apart from the large cold storage chambers for long-term storage, refrigeration system is also required for on-farm or in production catchment for agricultural crops during short-term storage. However, designing an on-farm cold storage is a challenge due to its complexities during design and refrigeration system. In this paper, a software, ‘HimSaurya’ was developed for Solar PV powered on-farm cold storage design. It was developed in Visual Studio Express Desktop 2012 environment. Cold storage structural design, refrigeration system equipment and solar PV panel design were implemented in Himsaurya. The vapor absorption system (VAS) was adopted in cold storage refrigeration system. An optimized energy efficiency was also investigated further using the HOMER software. The sensitivity of HimSaurya was assessed for different tropical, and subtropical agricultural produce e.g. mango, sapota, strawberry, and tomato. Results are showing a linear trend in cooling load with respect to product storage capacity. The results are promising with improving storage quality and reducing wastage of perishable agricultural produce.

Numerical Modelling of Heat and Mass Transfer in Vegetables Cold Storage

Heat and mass transfer phenomena occurring in cold storage chambers for vegetables have been modelled in the paper on the example of the experimental Chinese cabbage cold store. Special attention has been given to the problem of modelling of interrelationship between phenomena occurring in the bulk of vegetables and in the heat exchanger of a cooling unit, accomplished through User Defined Functions UDF so that the cooling capacity and the transpiration and respiration in the bed of cabbage were closely related. The comparisons between simulation and experimental results were conducted in order to indicate further improvements to the model.

English

The optimum condition for storage of 'Laetitia' plums (Prunus salicina) under controlled atmosphere (CA) is not currently known. This study was aimed at assessing the effects of controlled atmospheric (CA) conditions on the postharvest quality preservation of ‘Laetitia’ plums. Besides regular atmosphere (RA; 21kPa O2 + 0.03 kPa CO2) as condition/treatment control, the following CA conditions (kPa O2 + kPa CO2) were assessed: 1+3; 1+5; 2+5; 2+10; and 11+10. In all cases, the fruit were stored for 60 days at 0.5°C±0.1°C and 96±2% of relative humidity (RH). Upon removal from the cold storage chamber and after four days in ambient conditions (20±2°C/60±5% RH), the fruit were assessed in terms of: respiration and ethylene production rates; flesh firmness; texture; titrable acidity; red color index and hue angle (ho) of the skin; incidence of fruit cracking and internal breakdown (flesh browning). The fruit stored under the different CA conditions presented lower respiration and ethylene production rates, higher values of flesh firmness, texture and titrable acidity, lower development of skin red color, and lower incidence of skin cracking compared to the fruit under RA. CA conditions of 2+5, 1+5, and 1+3 resulted in a more substantial delay of ripening. CA conditions of 2+5 and 1+3 resulted in lower incidence of internal breakdown. Key words: Ripening, physiological disorder, postharvest, Prunus salicina.

Simulation and optimization of energy consumption in cold storage chambers from the horticultural industry

The use of industrial cooling for food preservation has been revealed to be an efficient and widely employed technique, from harvest time to final consumption by the customer. However, the most used method to generate that cold (based on the compression refrigeration cycle) requires a considerable amount of electric energy, especially if no appropriate energy efficiency measures are implemented in cold storage chambers. This fact contributes to the increased costs in electricity bills, reduction of competitiveness among companies and also to a negative impact in terms of global warming. To help companies define and implement the right efficiency measures for cold production, this work aims to develop a methodology for simulation and optimization of energy consumption in cold chambers by improving both constructive and operating parameters (external temperature, enclosure insulation, door opening time, etc.), which contribute to the infiltration of heat energy. It is also intended that this methodology determines which of those parameters have greater influence in energy consumptions, as well as to estimate possible savings resulting from the optimization process. Results obtained in a garlic cold chamber showed that it is possible to achieve energy savings of up to 40 % for an initial investment around 1,500 € in efficiency measures and a payback time among 2 and 5 years. On the other hand, parameters that had the greatest influence in energy consumptions were those directly related with thermal insulation of enclosures and entry of warm air within. Total contribution of these two parameters in the global consumption was about 95 %.