Cold Storage System Research Articles

Experimental Investigation on Enhanced Energy Storage Characteristics of Spherically Encapsulated 1-Decanol/Expanded Graphite Composite for Cold Storage System

The low solidification temperature (0°C), sporadic nucleation behaviour and supercooling phenomenon of ice are the major factors affecting the energy storage efficiency of an ice-based cold thermal energy storage system (CTESS). Due to the non-supercooling nature and high solidification temperature (~4.1°C), 1-Decanol-Expanded graphite composite (CPCM) is proposed as a prospective replacement for ice in CTESS. The CPCM was macro encapsulated inside the various diameter (42, 51 and 64 mm) spherical enclosures (S.Es), and its energy storage performance was studied at different wall temperatures (Tw) for charging (0,-3 and -6°C) and discharging (10, 13 and 16°C). It is found that the latent heat can be stored in CPCM even at a higher wall temperature (-3°C), which is not possible in the case of ice. To freeze the same mass of 1-Decanol at Tw = -6°C, the CPCM filled 51 mm S.E requires 85.37% lower time than that of PCM filled S.E. Based on experimental results, -3 and 13°C is found as an optimum wall temperature for charging and discharging, respectively. The charging and discharging rates increase with diameter. Besides, in a 51 mm S.E, the time required to store (Tw = -3°C) and recover (Tw = 16°C) a stated amount of energy in CPCM is 81.27%, and 76.45% lower than that of PCM, respectively. CPCM has superior phase change and energy storage characteristics. Therefore, the use of CPCM in CTESS ensures effective storage and recovery of cold energy.

Optimization of operation strategy for a grid interactive regional energy system

With the rapid development of power demand response in grid interactive building, it is urgent for regional energy system with great power flexibility potential to realize the interaction with grid. The power flexibility of regional energy system can be divided into direct power flexibility and power flexibility transformed from thermal flexibility. The former comes from power generation system and power storage equipment, whereas the latter comes from cold (heat) storage system. To improve the power flexibility and economy of regional energy stations, this paper proposes a TOU-price-based optimization model for the operation strategy for a grid interactive regional energy system. The model optimizes the hourly load distribution of the direct energy supply system and the energy storage system to achieve load transfer without affecting user comfort requirements, to maximize the power flexibility, and to improve the economy of the system. The proposed model can serve as reference for the operation strategy optimization and the system design of other existing or new regional energy systems. On the basis of experimental comparison and simulation analysis, the accuracy and rationality of the optimization strategy are verified.

Fabrication and Performance Evaluation of Cold Thermal Energy Storage Tanks Operating in Water Chiller Air Conditioning System

In this study, cold and thermal storage systems were designed and manufactured to operate in combination with the water chiller air-conditioning system of 105.5 kW capacity, with the aim of reducing operating costs and maximizing energy efficiency. The cold storage tank used a mixture of water and 10 wt.% glycerin as a phase-change material (PCM), while water was used as heat transfer fluid (HTF). The cold storage heat exchanger was made of polyvinyl chloride (PVC). On the other hand, the thermal storage tank used water as the storage fluid with a capacity of 50 L of hot water per hour. The thermal storage did not use a pump for water transfer through the heat exchanger, so as to save energy and operating costs. In this paper, the operating parameters of the cold and thermal storage tanks are shown according to the results of experimental research, including the temperatures of cooling and heating load, heat transfer fluid, and cold storage material during the discharge process, as well as the discharge duration. The system assisted the air conditioner in cooling the internship workshop space at the university with an area of 400 m2, contributing to a remarkable reduction in air-conditioning system operating costs during the daytime. Furthermore, the system recovered waste heat from the compressor of the water chiller, and a thermal storage system was successfully built and operated, providing 50 L of hot water at a temperature of 60 °C per hour to serve the everyday needs of school students. This design was suitable for the joint operation of cold and thermal storage tanks and the water chiller air-conditioning system for cooling and heating applications.

Experimental investigation of a multi-kWh cold storage device based on phase change materials

An innovative technology to store cold energy for civil applications and based on Phase Change Materials (PCM) is presented and experimentally validated. The storage tank is coupled to a hydronic chiller in a Heating, Ventilation and Air Conditioning (HVAC) system with the aim of optimizing its performance shaving the cold energy peaks required by the users. The system is composed of a tank containing a heterogeneous mixture of an organic PCM and water. The two liquids are immiscible and water is stratified in the lower part of the tank, PCM in the upper part. A coaxial water-water heat exchanger is immersed in the PCM volume. Water stream from HVAC system (primary circuit) and the water contained in the storage tank (secondary circuit) are fed to the heat exchanger. Then, the secondary circuit water is sent back to the top of the tank through nozzles and the water drops descend by gravity into the volume of PCM. By this way, the PCM is solidified uniformly and quickly, and cold energy is stored in the form of latent heat. In this paper, a prototype able to store up to 25 kWh of energy through PCM solidification is presented. A detailed testing campaign is carried out and an optimized strategy for the cold energy storage system operation is proposed. The experimental results demonstrates that the tank is fully charged in 2.5 h and discharged in 1.6 h.

Aspects of adapting the cooling installation in a food cold storage system to the applicable f-gas regulations

The paper presents the methodology of the analysis of the cooling system reconstruction in a food cold store under the regulations applicable from the beginning of 2020. They result from the so-called the F-Gas Act concerns the use of refrigerants with a low environmental impact. First, the elements of the existing regulations on the use of refrigerants were discussed. This part of article focus mainly on the F-Gas Act and the regulations it entails. Then, the refrigerants used so far in refrigeration systems were compared with substitutes, which were the only ones that have been approved for use since 2020, thanks to the low GWP index. Their properties are briefly described, along with the benefits (primarily for the environment) of their use. The main part of the work is the analysis of the reconstruction of the cooling system to use an alternative refrigerant. During the work, the construction of the cold storage was analyzed together with the system currently working in analysed location. Then, the heat balance was calculated, thanks to which it was possible to determine the demand for cold. Than, several refrigerants that meet the latest standards and application regulations were selected. Their operating parameters were examined, the possible variants of use were compared in relation to the determined demand for cooling and the most important operational features were summarized.

Performance analysis of cold storage system with nanofiller phase change material

Performance analysis of cold storage system with nanofiller phase change material

Numerical study of a positive latent cold storage system for industrial applications: Discharge mode

In this work, a comprehensive numerical study on a latent heat storage system is presented. The adopted storage system consists of a tank with a fixed bed of phase-change materials (PCMs). A numerical model simulating the dynamic and thermal behaviour of this system during the discharge period has been developed and validated using experimental data from the literature. During the discharge mode, when the inlet heat transfer fluid (HTF) is maintained at a temperature near the melting temperature of the PCM, a quasi-stabilization of the outlet HTF temperature is observed. The duration of the discharged energy is increased when the flowrate of the fluid is decreased. A detailed study was also carried out to better understand the behaviour of latent storage system using multiple PCMs. The obtained results for a multi-PCM configurations reveal that the latent energy released during the discharge period depends on the placement order of the PCMs inside the tank, the flow rate of the HTF and the level temperature of the HTF at the inlet to the tank. This numerical study could a be a key solution in industrial cold applications such as air conditioning and thermal comfort, the medical and food sectors.

Enhancement of the round-trip efficiency of liquid air energy storage (LAES) system using cascade cold storage units

In this research, the variation of round-trip efficiency in a liquid air energy storage system (LAES) is calculated and an optimal configuration is found. The multiple stages of cold energy storage are simulated with several materials that process latent heat at different temperature ranges. The effectiveness in the charging and discharging processes of LAES is newly defined, and its relationship with the round-trip efficiency is examined. According to defined correlation, the effectiveness of the discharging process significantly affects the overall system performance. The round-trip efficiency is calculated for the combined cold energy storage materials of aqueous dimethyl sulfoxide (DMSO) solution, ethanol, and pentane theoretically. The performance of LAES varies depending on the freezing point of the cold storage materials. In particular, when the LAES uses several cold storage materials, those materials whose freezing points are close to room temperature and liquid air temperature should be included in the cold storage materials. In this paper, it is assumed that only latent heat is used for cold energy storage, but for more realistic analyzes, the additional consideration of the transient thermal situation to utilize sensible heat is required. In the case of such a dynamic system, since there is certainly more increased heat capacity of the entire storage system, the volume of the cold energy storage system will be greatly reduced.

Developing A GIS-Based Approach for Enhancing Revenue Management of Fish Cold-Room Businesses in Oyo East Territory, Oyo State, Nigeria

Cold-room or Refrigerating Chamber is a post-harvest warehouse in which a specific temperature is artificially generated, maintained and purposely designed for storing products in an environment below the outside temperature. An ideal fish cold-room is a category of cold storage system usually design for frozen fish or kinds of seafood since the spoilage of post-harvest fish due to protein denaturation, fat changes and dehydration are experimentally slowed down by reducing the storage temperature. Fish is one of easily perishable protein foods that need careful handling but most traditional fish farmer in the study area always prefer to sell their fish in bulk at either profitable or unprofitable price during harvest time due to lack of adequate post-harvest fish preservative and processing techniques. Hence, the study aimed at developing GIS based approach for the available post-harvest fish cold-rooms in the study area to ensure effective control and management of revenue from this informal business. The objectives include: to determine the available number of fish storage cold-rooms and identify likely problems associated with cold-rooms storage businesses in the study area, to identify necessary practical measures for solving the so identified problems. Also, the methodology adopted includes database design, data acquisition using GPS and Scanner respectively and as well as creation of spatial and attribute database for the acquired Cold-rooms Storage Facilities using ArcGIS 10.2.2. Various results were generated that pointed in the direction of uneven distribution of the fish storage facilities. It is therefore recommended that it is necessary for various concerned Local Government Authorities to align with “Sustainable Development Goal’s Fourteen (SDGs14th) [1] on Food Security from Life below Water” by encouraging the establishment of adequate Modern Post-Harvest Cold-rooms Storage Facilities within their territory and equally ensure that they are always in good condition for public use.

Movable solar powered cold storage for fruits and vegetables

A solar powered portable cold storage system was designed and developed in 2017-18 for storage of fresh fruits and vegetables to increase the shelf life. The capacity of the cooling chamber is 3.88 m3. The cold store was operated atthree temperatures 8, 12 and 16ºC, respectively for 24 h. At 8ºC, the ranges of temperature and RH inside and outsidecold storage were 9.3–11ºC and 73.11–76.4% and 26.5–40.7ºC and 25.3–61%. At 12ºC, the ranges of temperature and RH inside and outside cold storage were 13–14.7 ºC and 68.2–77.7% and 28.7–42.1ºC and 26.0–45.5%. At 16ºC, the ranges of temperature and RH inside and outside cold storage were 17–18.1ºC and 72.9–79.3V and 29.5–43.9ºC and 22.2–50.1%. An average difference in temperature and RH of three setting temperatures (8, 12 and 16ºC) were 23.47, 21.94 and 18.90ºC and 33.63, 39.77 and 39.44% respectively. The average cooling efficiency of the developed cold storage for three setting temperatures was 91.26, 89.69 and 87.06 % respectively. This environment helped in keeping the vegetables fresh for significantly longer time. This cold storage structure is very useful for rural areas where there is shortage of electricity or its supply is erratic for storage of fresh fruits and vegetables.

Study on the interfacial thermal conductance between metals and phase change materials

Foam metal phase change composite materials and systems play a crucial role in the heat (cold) storage system. The interfacial thermal conductancebetween different foam metals and phase change materials under different phases isan important factor to affect the heat (cold) storage process of theheat (cold)storagesystem. In this paper, the interfacial thermal conductancebetween the three metals(copper, aluminum and nickel) andtwo phase change materials (paraffin and erythritol) in solid and liquidis measured by time-domain thermoreflectanctechnique. The experiments suggest that regardless of the types (paraffin or erythritol) and phases (solid or liquid) of phase change materials, the interfacial thermal conductance results preserve the same trend that copper < nickel < aluminum. By performing a series of molecular dynamics simulations and phonon-level analyses, the mechanisms for the above trend are identified to be the dominant contribution of lattice vibration in z direction and mismatching degrees of metal/phase change material interfaces. The interfacial thermal conductance of metals/paraffin are bigger than metals/erythritol in the same conditions.Compared with solid state, two kinds of phase change materials in liquid state show biggerinterfacialthermal conductance for all kinds of metals.

Liquid Air as an Energy Carrier for Liquefied Natural Gas Cold Energy Distribution in Cold Storage Systems

Liquid air can be employed as a carrier of cold energy obtained from liquefied natural gas (LNG) and surplus electricity. This study evaluates the potential of liquid air as a distributed source with a supply chain for a cold storage system using liquid air. Energy storing and distributing processes are conceptually designed and evaluated considering both the thermodynamic and economic aspects. Further, the proposed supply chain is compared with a conventional NH3/CO2 cascade refrigeration system. The thermodynamic analysis demonstrates that the exergy efficiency and the coefficient of performance of the proposed supply chain are 22% and 0.56, respectively. Economic analysis is based on a life cycle cost (LCC) evaluation. From the economic analysis, the liquid air production cost and the LCC of a liquid air cold storage system (LACS) are estimated to be 40.4 USD/ton and 34.2 MMUSD, respectively. The LCC is reduced by 19% in the LACS compared with the conventional refrigeration system. The proposed supply chain is economically feasible, although its thermodynamic performances are lower than those of the conventional system. The sensitivity analysis indicates that LNG mass flow rate in the air liquefaction system and the cold storage operating time are dominant parameters affecting the economic performance.

Design and development of an IoT enabled platform for remote monitoring and predictive maintenance of industrial equipment

Refrigerator and Cold Storage Systems (RCSS), also known as cold chain are utilized in a wide variety of applications for the storage of sensitive goods. Consequently, there is a common need for optimal and continuous operation of the refrigerator group, including the freezing chamber and the compressor group. Therefore, under the framework of Industry 4.0, Internet of Things (IoT) enabling technologies can be utilized for the development of advanced tools which in turn can enable the remote monitoring of the refrigeration cycle as well as with the integration of intelligent algorithms to predict future malfunctions. This paper presents the design and development of a framework for the remote monitoring of RCSS based on the implementation of a Wireless Sensor Network (WSN) for data acquisition, and intelligent algorithms for Predictive Maintenance.

Experimental study on the charging and discharging behaviour of capric–lauric acid/oleic acid mixture in a cold thermal energy storage system for cold storage applications

In this study a capric–lauric acid/oleic acid mixture was synthesized to form a low temperature PCM for cold storage applications. An experimental investigation was carried out in a double helical coil cold thermal energy storage unit (CTESU) to study the charging and discharging behaviour of capric–lauric acid/oleic acid mixture. The inlet temperature and flow rate of the heat transfer fluid (HTF) were selected as experimental parameters to analyse the cold thermal energy storage performance of PCM. The analysis includes charging and discharging behaviour, energy dissipation rate, energy storage rate, energy charging efficiency, energy discharging efficiency and influence of HTF inlet temperature and flow rate under varied experimental parameters. With the increased contact area, the developed double helical coil considerably improves the heat transfer performance of the cold thermal energy storage unit. The discharging rate was 18% faster than the charging process due to predominance of natural convection. The PCM solidification during charging process is controlled by conduction. With increasing HTF flow rate during the discharging process, the melting rate was 16% higher than lower flow rates. In contrast, as flow rates increased, the charging rate did not change significantly. The role of natural convection and stratification which leads to unnecessary mixing of PCM consequently lowering the cooling energy stored. Also results suggest that capric–lauric acid/oleic acid can be utilized as a potential PCM for low temperature storage applications.

Structure and Price Dynamics of Potato Cold Storage in Gujarat

The present study was undertaken to study the structure and market dynamics of potato cold storages in Gujarat by collecting requisite information of ten cold storages from three major districts. It was observed that primary processing activities such as grading, sorting, and other value-added activities were taken place at the cold storage level. The cost of electricity was the major operational cost, followed by the cost of labour. Investment cost followed by the running cost of the cold storage was a major deterrent factor reported by the cold storage manager. The study concluded that there was a need to have the proper and effective strategies and policies to support the need to build an efficient cold storage system. Also, producer/trader/entrepreneur should undertake sorting and grading work at their harvest areas, reducing post-harvest losses and creating more bargaining power, and gaining more share in consumer rupees.

Experiment investigation on a LiBr-H2O concentration difference cold storage system driven by vapor compression heat pump

Solar-powered LiBr absorption cooling system is of potential in the application of air-conditioning. A LiBr-H2O concentration difference cold storage system driven by vapor compression heat pump was proposed. This cold storage process is not affected by the environmental conditions, since the main energy input is low price electricity at night. The experimental results show that the energy storage density (ESD) can reach 77.8 kWh/m3 and the energy storage coefficient of performance (ESCOP) is 2.81 with low heat loss. The ESCOP means the energy stored in the cold storage process divided by the total electricity consumption in the absorption and heat pump subsystem. The heat transfer in the condenser of the absorption subsystem approximately equals that in the evaporator of the heat pump, and the electricity consumption of the circulating pump in the absorption subsystem is low. Therefore, the value of ESCOP should be slightly lower than the COP of the heat pump system but for higher than 1. These results indicate the feasibility of improving the system efficiency, the operation cost, and long term operation of the solar air conditioning system by coupling the absorption and vapor compression cooling cycles. Finally, the influence of working parameters on the system performance is discussed based on the experimental and simulation analyses. The energy balance between the absorption cycle and the heat pump cycle in the cold storage system is analyzed. It is found that the coefficient of performance of the heat pump (COPele,HP) and ESCOP increase with a low initial LiBr-H2O solution concentration. The ESCOP decreases by 34.4% when the initial concentration increases from 52% to 57%. The average ESD increases to 140.2 kWh/m3 with a concentration difference of 8%. Based on the experiment results, the payback period of the proposed system is estimated as 2.4 years comparing with the traditional LiBr-H2O absorption system.

Preparation, characterisation and energy storage performance study on 1-Decanol-Expanded graphite composite PCM for air-conditioning cold storage system

Abstract Performance of a typical ice-based cold thermal energy storage system (CTESS) is immensely affected by its supercooling nature and low freezing temperature (0 °C). In this study, 1-Decanol (PCM) was recognised as a potential replacement for ice as it is cost-effective as well as having zero degree of supercooling, and high freezing temperature (5 °C). High thermal conductivity PCM-Expanded graphite (EG) composite (CPCM) was prepared by incorporating the PCM into the porous structure of EG. The thermal conductivity, specific heat, and thermal cycling stability of CPCM were studied. Further, the charging and discharging characteristics of CPCM were investigated in a 64 mm diameter spherical capsule at -3 °C and 13 °C wall temperatures, respectively. CPCM has an incorporation efficiency of 84.99%, and its thermal conductivity is 16.33 times higher than that of PCM. CPCM and PCM have good thermal reliability for 1000 cycles. The freezing temperature of CPCM is ∼4.1 °C higher than that of ice and its charging time is 81.85% lower than that of PCM, which signifies that the chiller operating time can be reduced by 81.85% to store the specified amount of energy in CPCM. Further, the time-averaged charging and discharging rate of CPCM is 5.51 and 5.97 times higher than that of PCM, respectively. Experimental results concede that CPCM is having high freezing temperature (∼4.1 °C), zero degree of supercooling and enhanced energy storage characteristics, which ensure that the utilisation of CPCM paves the way for efficiently storing and recovering the energy.

Design and testing of a high performance liquid phase cold storage system for liquid air energy storage

Liquid air energy storage is a promising large-scale energy storage technology for power grid peak-load shifting and reducing the volatility of renewable energy power generation. A high-efficiency cold storage subsystem of the liquid air energy storage system is important to guarantee good overall system performance. Liquid phase cold storage technology can avoid the heat conduction in the axial direction of that in the solid-phase media, which theoretically can achieve a higher cold storage efficiency. In this paper, the design method for liquid phase cold storage was proposed. A novel liquid air energy storage system with the compression power of 100 kW was built. The variation rules of the working medium temperatures, pressures and other key experimental results during the process of cold storage and release were tested. Results showed that the system achieved a 91.35% cold storage efficiency, providing an important basis for the liquid–air energy storage system to making it possible to gain a net round trip electricity to electricity efficiency to 50%. Methods to further improve the cold storage efficiency were also proposed in this paper.

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.

Investigation of cold storage performance to improve management of power generation in thermal power plants in Iran

During the hot seasons, the balance between power generation and consumption is disrupted due to the higher demand for cooling load and the lower power plant efficiency occurred due to the enhanced temperature of the inlet air to the turbine. The costly cold storage method in consumption centers (residential or official) is usually suggested to overcome the power generation problem in hot seasons. In this paper, the application of the cold storage system in the inlet of the gas turbine is proposed and the performance of the power generation system with cold storage is evaluated. The improvement of power generation with cold storage system compared to other cooling methods such as fog and electrical chiller, is discussed to determine which cooling method works best in reducing the network peak problem. Different methods of cold storage (partial/full) are also compared. The results for the proposed cooling system with cold storage used in hot seasons showed that, the 16-h cold storage method with the air condenser performed better during peak time compared to the other cooling methods. In June, July and August, this method improved the net generated power by 11.07%, 19.06% and 18.40%, respectively, compared with the normal condition of power plant without any cooling solution. the results of comparing the different storage strategies showed that the net output power in the full storage strategy was 2.14% higher than the partial storage strategy. Using a water condenser instead of an air condenser results in a slight increase of 0.96% in the net power output of the turbine.