Cold Storage Refrigeration Research Articles

Parametric Based Techno‐Economic Evaluation for a Solar Thermal‐PV Integrated Multi‐Commodity Storage Facility

ABSTRACTPostharvest losses and spoilage of agricultural products are a major problem for tropical countries, and it is even more challenging for countries encountering fluctuating power shortages, such as Pakistan. Therefore, this study focused on the energy and economic analysis of cold storage to store three products (potatoes, pomegranates, and potatoes) according to the season and storage span throughout the year. The cooling load of the cold store was supported by a LiBr‐H2O vapor absorption and vapor compression refrigeration system to maintain the desired temperature for each product during cold storage. A solar thermal PV system is installed to operate cold storage refrigeration systems. Cold storage performance was analyzed by developing thermal models of integrated systems using the ambient conditions of Lahore, Pakistan. A parametric study was also conducted to analyze the impact of various working parameters on integrated system performance, and it was found that the maximum peak cooling load of 91 kW inside cold storage is attributed to pomegranates owing to high ambient conditions during its loading month. The product loading rate significantly affects the cooling load of cold storage and varies directly with it, as observed for an increase in the product loading rate from 0 to 50 000 kg/day cooling load also increases from 34 to 87 kW. To meet the thermal demand of the generator of the vapor absorption system, parabolic troughs were installed to operate cold storage, and it was found that a minimum of four PTC were needed to support the peak cooling load at the maximum product loading rate and minimum DNI value. To meet the electrical demand of cold storage electrical equipment and the compressor of the vapor compression system, solar photovoltaic panels were installed, and it was found that a minimum of 618 panels was required at a minimum tilted radiation value. To validate the viability of proposed design system economic analysis was also conducted which revealed a payback period of 12 years for Kinnow and potatoes and 16 years for pomegranates.

Impact of control strategies on energy consumption in cold storage facilities

The fast development of global cold chains has led to a rapid increase in cold storage facilities capacity, in which consumes substantial amounts of energy. However, limited research has been conducted on the energy consumed by cold storage facilities, and the time and economic costs of obtaining long-term measurements of annual energy consumption of cold storage facilities are high. Therefore, in this study, short-term field tests and simulations were combined to establish a transient thermal network model for cold storage, using a specific cold storage case study for validation. The model considers the structure of the hall, which strongly impacts the cooling load. The refrigeration system performance was analyzed on the measured data. Literature and field research have shown temperature range control to be the baseline control strategy used in cold storage refrigeration systems, which ensures that the cold storage temperature remains within the set temperature range at all times. In addition, some researchers have proposed a control strategy based on time-of-use tariff that provides cooling almost throughout the valley period. These two control strategies were applied to frozen and chilled rooms, separately; the results indicated that for both frozen and chilled rooms, the latter control strategy consumes slightly less energy than the former strategy. However, the electricity bill for the latter control strategy are 0.35 and 0.5 times lower than those for the former strategy for frozen rooms and chilled rooms, respectively.

Enhanced magnetocaloric and cold storage properties in HoCu2-xNix (x=0.05–0.5) compounds for hydrogen liquefaction

Based on first-principle calculations and experiments, the electronic structure, magnetism, magnetocaloric effect and cold storage properties of HoCu2-xNix (x=0.05–0.5) compounds have been investigated. The theoretical calculations revealed that the magnetic interactions of the HoCu2-xNix compounds were gradually transformed to ferromagnetic states when the Ni element was added above 0.0625. In addition, the Ni element leads to a decreasing Fermi energy level, which results in a significant enhancement of orbital hybridization around the Fermi surface, which may be responsible for the magnetic jump. The magnetic phase transition temperatures of the HoCu1.75Ni0.25 and HoCu1.5Ni0.5 compounds are 14.4 K and 26.0 K, respectively. The ferromagnetic state transition is responsible for the excellent magnetocaloric effect of the HoCu2-xNix compounds under low magnetic fields. The maximum magnetic entropy changes of the HoCu1.75Ni0.25 and HoCu1.5Ni0.5 compounds were 14.7 J/kg K and 11.5 J/kg under varying magnetic fields from 0 to 2 T. In addition, the Ni element make the HoCu2 compound exhibit more excellent cold storage capability. The peak of specific heat capacities of HoCu1.75Ni0.25 and HoCu1.5Ni0.5 compounds were 0.6 J/cm−3K−1 and 0.9 J/cm−3K−1 under 0 T. The present results indicate that HoCu2-xNix (x=0.05–0.5) compounds have promising applications in cryogenic cold storage and magnetic refrigeration.

Efficiency comparison between defrosting methods: A laboratory study on reverse-cycle defrosting, electric heating defrosting, and warm brine defrosting

Frost on the evaporator of a cold storage refrigeration system reduces cooling capacity and COP (Coefficient of Performance). Hence an energy-efficient defrosting process is crucial for economical operation. Various defrosting methods have been proposed in literature and their defrosting efficiency has been assessed. However, differing experimental conditions, e.g., variations in evaporator geometry and diverse air conditions, hinder accurate comparison across literature. Further, while electric heating defrosting (EHD) and reversed cycle defrosting (RCD) methods are widely studied, warm brine defrosting (WBD) method is rarely investigated. Despite this, WBD offers the potential to use low-temperature waste heat for defrosting, which reduces energy consumption drastically. Therefore, this study experimentally assesses the defrosting efficiency for EHD, RCD, and WBD on a single experimental setup, thus ensuring comparability. For the first time, low brine supply temperatures (10 °C/20 °C/30 °C) for WBD are investigated. Our results show that RCD reaches the highest defrosting speeds and has the highest defrosting efficiency between 56% and 61%, depending on air conditions. WBD at10 °C and 20 °C exhibit low efficiencies of 16–29%. However, WBD at 30 °C has comparable efficiency to EHD (40–45%). The reported results can serve as a decision criterion in the design process of refrigeration systems.

Thermodynamic evaluation of two-stage refrigeration cycle with deep intercooling and series-parallel integration of thermal and mechanical compression

ABSTRACT A novel two-stage refrigeration cycle with deep intercooling and series-parallel integration of thermal and mechanical compression is proposed. Its mechanical energy consumption can be reduced by supplementing it with low-grade non-large-scale heat sources. Firstly, to show the advantages of the proposed cycle, the comparison with a two-stage refrigeration cycle with series integration of thermal and mechanical compression as well as the cascade system driven by heat and power is implemented. Secondly, the effects of the major operating parameters affecting the performance such as inter-stage pressure, inlet quality of high-pressure stage mechanical compressor and thermal compressor flow rate are analyzed. Finally, the near-optimal operating parameters for different working conditions are proposed. It is exhibited that the ECOP of the proposed layout increases by 19.4–43.7% as compared to the traditional system layouts. It is recommended that the inlet quality of 0.9 in the high-pressure mechanical compressor serves as a good guide for different operational conditions. The results show that the proposed system has a clear potential of lowering the energy consumption of cold storage refrigeration systems by supplementing with available low-grade heat. It is believed that the proposed cycle promotes a more sustainable development of fresh produce e-commerce logistics.

Oil droplet spread on an immiscible surface of a vertically falling liquid film

Droplet spread over a vertically falling liquid film is studied in this paper. A simulation model is built and verified by experiment. Following this, a unique phenomenon that emerges in this context, namely, a strong inertial oscillation in an early stage of spreading, is analyzed. Finally, the equilibrium features of an oil droplet in this circumstance are discussed. The results show that the maximum spreading length in a strong inertial oscillation is much longer than the equilibrium length, being 152% the length of the latter in the base case. Furthermore, the equilibrium spreading length increases nearly linearly with the initial diameter of the droplet. The paper provides data to understand the effects of an oil droplet on a vertically falling film absorber to promote energy saving in a cold storage refrigeration system with low-grade heat.

Measures to expand the application range of ammonia refrigerant

To cope with the climate issue, China has clearly stated the goal of carbon peaking and carbon neutrality. Most of the refrigerants currently used are HCFCs and HFCs refrigerants. These refrigerants have high COP and GWP values and can cause a severe impact on the environment. Ammonia refrigerant is an environmentally friendly natural refrigerant, ODP and COP value are zero, and the cost is low, with significant environmental and operational advantages, large unit cooling capacity, moderate condensing temperature, good thermal conductivity, suitable for refrigerator and cold storage refrigeration, but at the same time ammonia is a toxic gas with a strong pungent odor. Studying measures to expand the application range of ammonia refrigerants is conducive to correctly understanding and using ammonia refrigerants and giving full play to the refrigeration potential of ammonia refrigerants. Promoting the utilization of ammonia, a clean energy, and achieve the purpose of environmental protection.

Effect of refrigeration and freezing on the oxidative stability of WB chicken breast

Wooden Breast (WB) myopathy has been observed in fast growing birds and is characterized by partial or full hardness of the Pectoralis major muscle. The aim of this study was to investigate the effect of cold storage (refrigeration and freezing) of severe WB chicken breasts (WBS) on lipid and protein oxidative reactions. A total of 15 WBS chicken breasts and 15 normal chicken breasts (N), with no myopathy, were used in this study. Chicken breasts were stored under refrigeration (1 ± 2 °C) for 0, 11 and 14 days, and freezing (−18 ± 2 °C) for 0, 45 and 90 days, with 3 chicken breasts per sample being sampled for each time, except for day 0, with samples being the same for both storage conditions. WBS chicken breasts exhibited lower protein content and higher lipid and moisture content compared to N samples. Regarding storage type, freezing did not impact lipid oxidation of WBS chicken breasts; however, refrigerated storage reduced TBARS and WOF levels. Total protein carbonyl content was significantly impacted by refrigerated storage (30% increase) and freezing (140% increase). Regardless of storage type, WBS samples were more oxidized (lipids and proteins) compared to normal samples (N).

Experimental study on performance of double-mode refrigeration system

To ensure energy-saving and environment-friendly operation of multifunctional cold storage refrigeration systems, an experimental platform for a double-mode refrigeration system (DMRS) has been built, which can realize both a single-compression refrigeration cycle (SRC) and a cascade refrigeration cycle with a single refrigerant (CRC). The variable-frequency characteristics and control strategy of two modes were experimentally studied. The results show that with an increase in the low-temperature stage compressor frequency, there exist an optimal COP and optimal compressor frequency, the optimum frequency increases with a decrease in evaporation temperature and condensation temperature. When the condensation temperatures are 45, 40, and 35 °C, the evaporation temperature switching values of the refrigeration capacity are 2.5, −1.2, and −4.1 °C, respectively, and the evaporation temperature switching values of the COP are −10.6, −15.0, and −19.1 °C, respectively; and a control strategy of mode switching and compressor frequency adjustment is summed. When the system is running between two modes, the compression ratio is below 6, the discharge temperature is below 100 °C, and as the evaporation temperature increases from −35 °C to 10 °C, the COP of the system at 45 °C, 40 °C and 35 °C varies from 0.98 to 3.54, 1.20 to 4.27 and 1.42 to 5.20 respectively.

Assessment and optimization of solar absorption-subcooled compression hybrid cooling system for cold storage

The solar absorption-subcooled compression hybrid cooling system is an economically viable energy-saving solution for cold storage refrigeration system. However, the thermodynamic and economic performance of this system has not been assessed specifically for cold storage. Additionally, the system performance strongly depends on the appropriate design of critical parameters, which has not been previously analyzed either. Therefore, a technical and financial evaluation of the solar absorption-subcooled compression hybrid cooling system for cold storage is implemented systematically in this study based on the simulation of the typical days. The effects of the absorption subsystem size and storage tank volume are analyzed. Furthermore, global optimization is performed using the genetic algorithm. It is determined the optimal design is as follows an absorption subsystem size of 0.04–0.06 kW/m2 with a storage tank volume of 40–60 L/m2 for the case in which the collector area (2000 m2) is half the available area. The peak annual electric energy savings is 68.8 kWh/m2. The solar absorption-subcooled compression hybrid cooling system is economically viable for cold storage without any subsidy and the minimum payback period is 4.96 y. This study can be beneficial for the effective and feasible reduction of the energy consumption of cold storage refrigeration systems.

Effect of various phase change materials (paraffin wax/hydrogenated vegetable oil) packed in a fabricated shell and tube type heat exchanger

Researchers are often trying to find out the various renewable energy sources to continuously feed the growing energy demands as well as storing the generated energy with appropriate known technology. In line of the above, in order to store the energy, phase changing material (PCM) playing the major role. The phase changing materials exhibit better efficiency due to its energy storage capacity, and keep supplies constant thermal energy when need arises. Normally the characteristics of the phase change materials are charging, storing and following this, final step is discharging the heat to the selected medium through the phase changing materials and the same could be used for many applications starts from domestic to industrial spectrum. In this present study, the paraffin wax and hydrogenated vegetable oil have been used as the phase changing materials. To experimentally analyze the coefficient of thermal expansion of the phase changing material, the tube and shell type heat exchanger have been used. Similarly the efficiencies of the thermal energy storage (TES) capacity of the subjected material have been verified, with the intention of employ the same system for the applications like cold storage plant, refrigeration, domestic heating and automobile sectors.

Thermal performance of triplex-tube latent heat storage exchanger: simultaneous heat storage and hot water supply via condensation heat recovery

In refrigeration system, refrigerant condensing will release a lot of heat. Using condensation heat from cold storage refrigeration system to provide heat for domestic hot water preparation and industrial hot water supply promotes energy conservation, and latent heat thermal energy storage (LHTES) has unique advantages. Compared with the shell-and-tube heat exchanger, the triplex-tube heat exchanger (TTHE) can achieve simultaneous heat storage and hot water preparation, but few studies have investigated the thermal performance. A mathematical model of TTHE is established by enthalpy method, and the dynamic characteristics has been studied. The results show that liquid sensible heat transfer, latent heat transfer and solid sensible heat transfer are three stages experience in the whole process. The heat storage rate increases and the heat release rate decreases gradually with the opposite trend, but finally reaches to balance with a stable value. The higher the HTF inlet temperature is, the higher the outlet temperature is, but the temperature difference in stable stage is smaller. With the increase of mass flow rate, its effect on heat release gradually weakened. Under the calculation conditions, phase change material with 80 °C transformation temperature for cold storage refrigeration system condensing heat recovery is reasonable.

Fuzzy Control of Cold Storage Refrigeration System with Dynamic Coupling Compensation

Cold storage refrigeration systems possess the characteristics of multiple input and output and strong coupling, which brings challenges to the optimize control. To reduce the adverse effects of the coupling and improve the overall control performance of cold storage refrigeration systems, a control strategy with dynamic coupling compensation was studied. First, dynamic model of a cold storage refrigeration system was established based on the requirements of the control system. At the same time, the coupling between the components was studied. Second, to reduce the adverse effects of the coupling, a fuzzy controller with dynamic coupling compensation was designed. As for the fuzzy controller, a self-tuning fuzzy controller was served as the primary controller, and an adaptive neural network was adopted to compensate the dynamic coupling. Finally, the proposed control strategy was employed to the cold storage refrigeration system, and simulations were carried out in the condition of start-up, variable load, and variable degree of superheat, respectively. The simulation results verify the effectiveness of the fuzzy control method with dynamic coupling compensation.

Hyperbaric cold storage versus conventional refrigeration for extending the shelf-life of hake loins

Today, extending the shelf-life of fish, while retaining the organoleptic properties of the product, is still a challenge. To compare the effectiveness of conventional and hyperbaric cold storage in preserving fish quality, we stored Cape hake loins at 5 °C, both at atmospheric pressure and at 50 MPa. After 7 days of storage, microbial counts and total volatile basic-nitrogen content in conventionally refrigerated samples exceeded the limits recommended for consumption. By contrast, hyperbaric cold storage maintained these parameters unaltered, although it produced drip losses close to 5% and increased the shear resistance and whiteness of the raw samples by 44% and 9%, respectively. Nevertheless, after cooking, weight losses were less than half of those of the control loins and whiteness differences disappeared. Consequently, the sensorial analysis could only find moderate differences between the samples before and after hyperbaric storage. These results clearly prove that hyperbaric cold storage was more efficient than conventional refrigeration for the preservation of hake loins. Hyperbaric cold storage opens interesting new doors for the fish-processing industry. Thus, it could be employed in different sections of the cold chain: on board, immediately after caught; at the food industry, during processing; on ship or trunk transport for long-distance markets; at school or hospital kitchens; at restaurants; or even at home. The increased cost resulting from hyperbaric storage should be overcome by an extended shelf life of a high-quality product.

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.

Ice Based Energy Storage Integration with Solar PV Power Plants for Cooling Energy

This paper gives aspects of the design of Cooling Thermal Energy Storage (CTES) for cold storage refrigeration and building air conditioning plants, powered/integrated through Solar Photo Voltaic (SPV) power. Ice based CTES are useful when there is mismatch between the availability of the energy source (grid tied centralized system or roof top decentralized system) and the air conditioning/ refrigeration application period. In both grid power with time of the day metering or SPV powered systems in integrated as well as in decentralized SPV, the source-load mismatch is handled through an ice storage system. The ice storage system not only helps with operation under decoupled source-load environment but gives the benefits of reduction in maximum output power, average power and energy consumption by 20-40 % as compared to conventional systems in centralized as well as decentralized environments.

Cold storage condensation heat recovery system with a novel composite phase change material

Using condensation heat from cold storage refrigeration systems to provide heat for domestic hot water preparation and industrial hot water supply promotes energy conservation. However, few studies have investigated cold storage condensation heat recovery using phase change materials (PCMs). In this study, a cold storage condensation heat recovery system that uses PCMs has been designed and analysed. According to the principle of energy cascade recycling, different operation modes could be effectively switched to recycle condensation heat. Furthermore, a novel and suitable phase change composite material is developed for cold storage condensation heat recovery, which has a relatively large latent heat, high thermal conductivity, and an appropriate phase change temperature (i.e. 80°C). With carnauba wax (CW) as the PCM and expanded graphite (EG) as the additive, a composite was developed with an optimal mass ratio of CW:EG=10:1. The thermal and physical properties and the interior structure of the composite were then investigated using a scanning electron microscope (SEM), thermal constants analyser (Hot Disk), differential scanning calorimeter (DSC), and Fourier transform infrared spectrometer (FT-IR). Furthermore, experiments on the melting and solidification processes and accelerated thermal cycling were also conducted. It was found that at the optimal mass ratio of 10:1, the temperatures of the CW/EG composite in the melting and solidification processes were 81.98°C and 80.43°C, respectively, while the corresponding latent heats were 150.9J/g and 142.6J/g, respectively. During both processes, CW could retain its original worm-like structure after being completely adsorbed by EG. Compared to only CW, the melting and solidification time of the CW/EG composite were reduced by 81.7% and 55.3%, respectively, while its thermal conductivity was 16.4 times higher. After 1000 runs of accelerated thermal cycling, the endothermic/exothermic phase change temperatures of CW and the CW/EG composite increased by only 0.42%/0.42% and 0.23%/0.27%, respectively, while their endothermic/exothermic latent heats decreased by 4.96%/4.78% and 2.05%/3.44%, respectively. These results indicate that both CW and the CW/EG composite have excellent thermal reliability, while the CW/EG composite exhibits a slightly better performance. Finally, the experiments show that the CW/EG composite has desirable thermal and physical properties such as high thermal conductivity and reliability; Hence, it has good potential as a material for facilitating condensation heat recovery from cold storage refrigeration systems.

Performance analysis of a solar-assisted OTEC cycle for power generation and fishery cold storage refrigeration

The cold storage in fishery industry is in great demand in tropical coastal regions. This research proposes an ocean thermal energy conversion (OTEC) based solar-assisted combined power and refrigeration cycle, which can be used for both electricity generation and fishery cold storage application. In this proposed combined cycle, the ammonia/water is selected as the working fluid and the warm/cold seawater is utilized as the heating/cooling source. A two-stage ejector system is introduced, the turbine is used to produce power and the evaporator is used to produce refrigeration output. Besides, a flat-plate solar collector is utilized to increase the heating source temperature. To evaluate the performance of the proposed cycle, a mathematical model is developed and a simulation program is developed; the performance comparison between it and a previous two-stage ejector OTEC cycle is made, which shows this solar-assisted cycle has a slightly lower power-production efficiency of 2.27% but a much higher comprehensive-production efficiency of 7.89% under the given working condition. Furthermore, parametric analysis is performed to guide the theoretical performance of this combined cycle. The results show that the generator pressure, solar collector outlet temperature and rich solution concentration all affect the cycle performance; the entrainment ratio of the first-stage ejector is greatly affected by the rich solution concentration.

IN VITRO SHOOT INITIATION OF Artocarpus heterophyllus Lam. (Jack fruit). Moraceae

Artocarpus heterophyllus is recognized as a versatile multipurpose tree species in alltropical countries. Its popularity is mainly due to its value as timber, food, fodder,fuelwood and a vast array of medicinal and other non-wood products.Seed propagation is the cheapest, easiest and most convenient method but hasdisadvantages in that the progeny may differ from the parent plant due to the high level ofcross-pollination. Vegetative propagation is very useful but has a relatively poor successrate. Developing a tissue culture technique for clonal propagation of the species will bevery useful for qualitative improvement of the plant with in vitro mutagenesis and cellhybridization.Four types of explants (mature embryos, apical meristems of young seedlings, apices frommature plants and nodal segments) were used in order to initiate shoots in vitro. Theembryos from seeds soaked in water for 24 hours produced shoots after 8 weeks ofincubation and the success rate was 50% while embryos from dry seeds only producedroots. There was no significant effect of cold storage (refrigeration) on shoot initiationfrom mature embryos.It has been found 88% of young apical meristems produced shoots in Campbell andDurzan medium compared to 60% in Murashige and Skoog medium. Only 1/ 3 ofproduced multiple shoots. Shoot initiation from nodal segments was a rare event. Callushas been produced from mature apices. Removal of the sheathing cover around the apexenhanced the shoot initiation from mature apices.

The Design Analysis of Cold Storage Refrigeration System Heat Recovery Coupled Solar Auxiliary Heated Drying Device

In order to effectively reduce the comprehensive energy consumption of the refrigeration system so as to achieve the purpose of energy saving and emission reduction, from a practical point of view, this design studied cold storage refrigeration system’s exhaust heat recovery device and its applications, which fully recovered the exhaust sensible heat of refrigeration system and combined with solar collector’s work to provide energy for materials drying. Through the design and matching of the solar collectors, exhaust heat recovery unit, dehumidification evaporator, drying chamber assembly structure and controlled atmosphere organization to achieve the device’s technical synthesis of freezing and drying, so as to realize a comprehensive energy consuming system of one input and two outputs, which provides a new direction for the energy-saving development of similar devices.