Ice Slurry System Research Articles

Sustainability and operational performance assessment of supermarket air-conditioning architectures using secondary fluids and slurries

Secondary loop architectures and phase change material (PCM) slurries could reduce the environmental impact of refrigeration and air-conditioning systems by lowering significantly the amount of primary refrigerants. However, there is a barrier to their industrial development due to the lack of studies on their behaviour in operational scenarios. The present work analyses the behaviour of different secondary loop systems in an industrial context, here the air conditioning of a supermarket in France. For this purpose, a generic approach, developed in previous work, is proposed to assess their potential of adoption. This modelling approach is able to describe the sustainability and operational performance (energy, environmental, economic, social) of refrigeration systems. After validation of the model on real architecture and components, five standard or new architectures were tested: centralized direct expansion system; secondary loop system with ethylene glycol water; secondary loop system with ice slurries, TBPB hydrate slurries or CO2 hydrate slurries. The main results of this study show that new secondary systems using hydrate slurries have better cooling energy performance than direct expansion or classical brine / ice slurry secondary systems. Moreover, even including pumping power, the life cycle climate performance of secondary loop systems is much better than that of direct expansion systems. However, the total cost of ownership of direct expansion systems is lower than that of secondary systems, but with little differences for smaller pipes. Finally, trade-offs between several performances can be proposed. For example, some architectures with suitable pipe diameters could meet TCO/LCCP-based and CAPEX/pumping-based trade-offs.

Performance Assessment of Solar Ice Slurry Cold Storage System for Solar Refrigerated Vehicle

This article mainly analyzes the ice slurry cold storage system in solar refrigerated vehicles, calculates and studies the thermal properties of the ice slurry, the cold load of the refrigerated vehicle, and the solar photovoltaic panels, and calculates the fuel savings of using solar power generation. Study the demand for ice slurry in ice slurry storage systems under different energy utilization efficiencies, analyze the economy of solar ice slurry generation systems, and calculate the recovery period of the system in this paper. The daily power generation of solar photovoltaic panels can run the electric motor for 2.93 hours. The solar refrigerated truck can save 7.91 liters of oil per day and reduce carbon dioxide emissions by 1.25×107 liters per day. The average annual electricity cost savings are 4026.67 CNY. Based on the total cost of the photovoltaic energy storage hybrid quality system, it will take 3.89 years to recover the cost. Calculate the density and enthalpy of the ice slurry based on the thermophysical model of the ice slurry, and provide different utilization amounts for the ice slurry mass generated by the ice slurry generation system at different efficiencies. Calculate the total weight of the ice slurry system.

Numerical Study on Flow-Melt Characteristics of Ice Slurry in Horizontal Straight Pipe with a Local Large Heat Flux Segment

Ice slurry is a high energy density coolant with excellent flow, phase change, and thermophysical properties. In order to investigate the recovery of ice slurry flowing through a local large heat flux segment, a 3D Eulerian-Eulerian model based on the granular kinetic theory considering the flow and melting phase change of ice slurry is developed. Sensitivity analysis of interphase forces is carried out. A comparison of the pressure drop, solid phase velocity, and heat transfer coefficient with empirical data is carried out, respectively. The calculated results are in good agreement with the experimental results, indicating that the numerical model could accurately describe the flow and melting characteristics. Thermophysical field distributions, the axial variation of ice volume fraction (IVF), recovery curve, the average heat transfer coefficient, as well as the re-uniformization length are obtained. After passing through local large heat flux segment, due to shear stress action, the IVF and the particle uniformity of the cross section have recovery characteristics. The gradient of the recovery curve decreases with increasing inlet IVF as well as with increasing Reynolds number. After the local large heat flux increases to a certain value, its effect on the recovery curve of the ice slurry is small. The re-uniformization length increases as the local large heat flux increases. The average heat transfer coefficient of local large heat flux segment increases due to damage of the boundary layer. These results can provide a theoretical basis for the design of ice slurry systems in practical application.

Application Analysis of Dynamic Ice Slurry System in Precooling of Fruit and Vegetable

Ice slurry precooling technology is a preservation technology that has unique advantages in the preservation of fruits and vegetables. It can make fruits and vegetables quickly drop to a suitable storage temperature. This paper summarizes the preparation methods of ice slurry, including the wall scraping method, undercooling method, vacuum method, fluidized bed method, and direct contact method. The wall scraping method, which has been widely used in industry and commerce, is the main method to design the dynamic ice slurry system between the buffer of fruit and vegetable air conditioning storehouse. Finally, this paper summarizes the characteristics and application of ice slurry precooling and makes a summary and prospect.

Investigating the performance of ice slurry system and the growth of ice crystals using seawater

This study investigates ice slurry systems, their transport characteristics, and seawater ice crystal formation through microscopy. Here, the salinity of seawater was set to vary between 10 and 30 ppt (part per thousand) and was used to form ice slurries. Pump flow rates were adjusted to be in between 5 and 30 L/min, while the scraper speed was set to vary at 350-550 RPM in positive correlation with the speed. It was discovered that ice slurries generated with a salinity of 10 ppt seawater had a significantly positive effect on ice production rate. Additionally, such ice slurries resulted in an intended reduction on the formation time of the ice slurries, while the flow and stirring rates were maintained between 10 to 15 L/min and 400 to 450 RPM, respectively. Additionally, the transport characteristics of the ice slurry were affected in terms of the increase in flow rate, salinity, and ice mass fraction. As an interesting threshold, the diameter of the ice crystals increased as storage time increased, and seawater concentration decreased, which was followed by agglomeration and the Ostwald ripening phenomenon. For cold storage applications, therefore, a low salinity of seawater (10-20 ppt) and 60 % ice mass fraction were recommended to deliver the best intended performance in an ice slurry system.

Slurry Ice as a Cooling System on 30 GT Fishing Vessel

Indonesia is the largest archipelago country in the world that has a sea area that is very spacious. Indonesian sea area is 5.8 million square kilometers and a coastline of 95 181 km has huge potential in the fisheries sector. In line with the need to further improve on the quality of the fish catch. One way to preserve fish is to use a slurry of ice. Slurry ice proved more effective preserving fishery products instead of using ice cubes. Ice slurry cooling system was designed and applied to the fishing vessel 30 GT. The cooling system uses a simple vapor compression system consists of five major components consisting of evaporator, condenser, compressor, and two pumps. In designing this system determined the type of refrigerant used in advance which type of refrigerant R-507a. Then do the design or selection of its main components. The design is only done on the evaporator. As for the other major components such as condensers, compressors, and pumps election in accordance with the specification of the power needed. After that dialakukan depiction of each system component. Then subsequently designing the laying of ice slurry cooling system components on a fishing vessel 30 GT. Through calculations using simple thermodynamic equations obtained cooling load on this system amounted to 32.06 kW. Condenser with a power of 40 kW. Compressor with power 12 kW. Pump with capacity 10 m3 / h. With memepertimbangkan space left on the ship in the ice slurry system design on the main deck of the ship to the efficient use of space on board. The power requirements of the generator vessel increases due to the addition of ice slurry system components therefore do replacement generator into the generator with a power of 100 kW and penambahn fuel tank to 6,000 L.

A novel ice slurry producing system with vacuum freezing

A novel vacuum ice slurry producing system with jet-pumps was proposed to deal with the problems of high energy consumption and ice blockage. In this novel system, one steam driven by a jet-pump was used to create vacuum in a hermetic vessel where water was sprayed through a nozzle to produce ice slurry, while the other steam was used to provide enough cold energy to make the left vapor in the hermetic vessel condense. Mathematical models of this novel system were established and theoretical simulation on the performance characteristics was also implemented based on the MATLAB program. Results show that the novel system is feasible and practicable, and the system performance is affected by many factors, such as the temperature of the generators, condensing temperature, evaporation temperature, and the cooling load of the refrigerator sub-system. The findings are helpful to improve the performance of ice slurry producing system.

Crystallization Kinetics and Crystal Morphology of Ice Slurry Produced by Vacuum

The mechanism by which ice slurry crystallizes under a vacuum was investigated in this work. The crystallization kinetic models for two different aqueous solutions (glycerol; a combination of glycerol and nano-SiO2) were developed based on the classic Avrami theory. The values of the Avrami exponent n under different experimental conditions were between 0.58 and 0.84, indicating the one-dimensional flake thickening growth of ice crystals. Glycerol inhibited the growth of ice crystals due to the hydroxyl-containing structure, and nano-SiO2, which served as a nucleating agent, could enhance the crystallization process effectively. The growth morphology of ice crystals, including the size and shape, were also observed. Results showed that ice crystals produced by the vacuum method were generally oval in shape. Adding nano-SiO2 to the glycerol solution reduced the size of the ice crystals, suggesting that nano-SiO2 is a promising additive for ice slurry systems. The study of crystallization mechanism of ice slurry can be useful for future design of vacuum ice production systems.

Study on sub-cooler based on the characteristics of the super-hydrophobic surface

Nowadays, it is a growing need for energy shortage and environmental protection, and therefore the development of air conditioning and cooling system with ice slurry system has an important significance and broad application prospect. The ice-making using sub-cooling water has become one of the most stressed dynamic ice-making methods because of its simple structure, high heat transfer efficiency and high ice-making efficiency. However, the ice blockage occurs too frequently, resulting in a discontinuous ice-making and reducing the efficiency of the system. Aiming at dealing with the ice blockage, the experiment with the super-hydrophobic sub-cooler has been carried out, which provides theoretical and experimental basis for the optimum design of the ice-making system. It was found that a large sub-cooling degree and a long lasting time of sub-cooling state can be obtained with the super-hydrophobic sub-cooler, increasing the yield of ice slurry. As a result, the efficiency of the ice-making system is improved, achieving the purpose of energy saving.

Proposed split-type vapor compression refrigerator for heat hazard control in deep mines

The thermodynamic performance of a proposed split-type vapor compression refrigerator (SVCR) for heat hazard control in a deep mine was numerically analyzed. The thermodynamic characteristics of the suction process of the proposed system were also simulated and analyzed. In the suction direction, the pressure, velocity, temperature, and specific enthalpy of R134a vapor dropped, whereas its specific volume and specific entropy rose. The variations in the superheat of the compressor inlet and the characteristics of the pressure drop of the suction process were also described in detail and analyzed. For comparison with the theoretical cycle, a variable, γ, defined as the COP ratio of the proposed system and the theoretical cycle, was presented, and the variations of γ were studied and discussed in detail. The proposed system was compared with a cooling water system and an ice slurry system, and results indicate that the thermal performance of the proposed system is better than that of the cooling water system. The thermal performance of the ice slurry system is better than that of the proposed system when a mine is sufficiently deep. However, when the mine is not too deep and the evaporation temperature, TE, is not too low, the proposed SVCR system is the better choice.

Evaluation of real-time ice concentration inside pipeline by the refractive index method

Ice fraction (or ice concentration, IC) of the ice slurry flowing through the pipe is very difficult to measure directly and in real time in ice slurry type system in thermal energy storage system. Measuring IC is very important to calculate the capacity of cold energy supplied through a pipeline. Ice fraction measurement methods have been reported as using density, electric resistance, electric conductivity, freezing point etc. However, the conventional methods are not perfect in terms of the resolution and accuracy. In this study, a new method is suggested to measure the IC of the ice slurry flowing through a pipe, which is used for a refractometer with low electrical noise and high resolution. To measure IC of the flowing ice slurry aqueous solution in pipe, it was installed in the test section to mass flow meter, refractometer, cyclone, and RTD (Resistance temperature detector) sensor. From the experiment, IC measurement method by using refractive index showed better result than others for the ice slurry in pipeline flowing or slurry tank.

Feasibility Analysis of a Novel Ice Slurry Producing System

Ice slurry is thought to be an ideal material for ice-storage because of its good performance on cold storage and transport. However, the conventional ice slurry producing methods heavily depend on electric power and have their own disadvantages. So, this paper proposed a novel ice slurry producing system which consists of three major cycles: the liquid desiccant deep dehumidification cycle, the evaporative precooling cycle and the evaporative supercooling cycle. Research was made by simulation analyses on each process and the whole system, in order to verify its performance. Results showed that the proposed system can alleviate the burden on electric power and has high ice-producing efficiency.

Crystallisation kinetics with nucleation phenomenon: Ice slurry system

In this paper a physical model is built to investigate the non-isothermal freezing kinetic in ice slurry systems. The global Nakamura-type kinetics is adopted to describe the nucleation rate during the freezing process. A genetic algorithm is used to determine the nucleation probability of ice slurry. The finite difference method is utilized to solve the heat transfer problem, and the source term method is employed to handle the absorbed latent heat. An experimental example of a cylindrical cell is used to test this model. From a comparison with the experimental result, the computed cooling curve is found to be very close to the experimental one.

Evaporation Characteristics of Single Water Droplet in Ice Slurry Production System of Evaporative Supercooled Water

To analyze the evaporation characteristics of single water droplet in the air with low temperature and low humidity, a theoretical model of droplet heat and mass transfer was proposed. The evaporation process of droplet in supercooled stage was simulated through theoretical model, results from modeling basically tallies with experiment, thus it is feasible to predict the evaporation characteristics of water droplet with smaller diameter by the mathematical model. The evaporative supercooled process of droplet in ice-slurry production system was calculated using the above-mentioned theoretical model. Results show that both the smaller droplet diameter and the lower droplet initial temperature can increase the cooling rate of water, in addition, the cooling rate can also be increased with the increase of air velocity or with the decrease of air temperature. Futhermore, droplet with lower supercooled temperature can be obtained with lower the air temperature. The initial droplet diameter less than 100µm can not only greatly improve the supercooling degree when the evaporative time of droplet is same, but also decrease the height of the ice making chamber.

A novel ice slurry producing system: Producing ice by utilizing inner waste heat

Ice storage is a potential energy saving method for air conditioning systems. An ice slurry is an ideal material for ice storage. The conventional ice slurry producing method using supercooled water suffers from the instability of ice block and depends heavily on electric power. A novel ice slurry producing system utilizing inner waste heat was proposed to improve this situation. This system consists of two major processes: an evaporative supercooling process and a liquid dehumidification process. Both theoretical and experimental works are presented about these two processes. Simulation analysis has been made on the evaporative supercooling process and the performance of the whole system. Experiments were performed about the two processes. The theoretical conclusion agrees well with the experimental results. Compared with the conventional system, this new system can alleviate the burden on electric power and raise the efficiency. Those improvements are essentially attributed to the reutilization of the inner waste heat generated from the system itself.

Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.

Thermodynamic Nonequilibrium in Ice-Slurry Systems

Compared with classical secondary refrigerant loops that continuously supply cold energy, ice-slurry systems rely on the use of storage tanks designed to store and supply the cold energy on demand; thus cutting off cooling peak demands. To reliably operate an ice-slurry cooling system, it is very important to know the ice-loading fraction within the ice-slurry storage tank and in the slurry transmission piping. In this paper we compare two ways to measure the local ice fraction inside the storage tank. The first method is based on a direct measure of the ice-slurry temperature, and the second one applies the differential scanning calorimetry technique.

Analyses of ice slurry formation using direct contact heat transfer

In the present study, ice slurry is produced by direct contact heat transfer between water and a coolant, Fluroinert FC 84. An analytical model has been developed to predict the growth of ice around the injected supercooled coolant droplets, which involves phase change and heat transfer between layers. During the journey of the coolant droplets through the ice generator, detachment of ice layer formed on the droplets occurs. Equations have been development to describe the process of detachment. Experiments were performed to validate the model developed to predict the ice generation. Parametric studies were then carried out on ice growth rate for different variables, such as droplet diameters and initial liquid temperatures. Both droplet diameters and initial liquid temperatures play an important role in the ice formation around the supercooled liquid surface. Ice growth rate increases with the increase of the droplet diameter, while the growth rate decreases with the increase of the initial temperature of the liquid droplet. For an ice slurry system, it is found that the predicted values of ice slurry generation are in good agreement with the experimental findings.

Vacuum freezing type ice slurry production using ethanol solution 1st report: Measurement of vapor–liquid equilibrium data of ethanol solution at 20°C and at the freezing temperature

In this study, an original method for the production of ice slurry from ethanol solution without using a refrigerator is proposed. This system has advantages compared with similar existing systems using materials other than ethanol solution. In this paper, the vapor–liquid equilibrium data of ethanol solution at 20 °C and at the freezing temperature are measured, which is necessary to calculate the COP of this ice slurry producing system. In the experiments, two experimental methods are proposed to measure the saturated pressure and the vapor composition of ethanol solution. Each method has an advantage in their operating temperature range. As a result, the vapor–liquid equilibrium diagrams of ethanol solution at 20 °C and at the freezing temperature, and approximations of saturated pressure of various concentrations of ethanol solution for varying liquid temperature, are obtained.

Numerical investigation of heat transfer and pressure drop characteristics of tube–fin heat exchangers in ice slurry HVAC system

This paper analyzes the heat transfer and pressure drop characteristics of a tube–fin heat exchanger in ice slurry HVAC system. Ice slurry is a suspension of crystallized water based - ice solution with a freezing point depressant like ethylene glycol. The ice- slurry is pumpable, hence it is also called pumpable ice. The composition of ice slurry considered for analysis is 14% ice fraction, 16% ethylene glycol, and 70% water by volume. It is deduced that the ice slurry HVAC system results in 7.4% increase in temperature drop over the conventional chilled water system The latent heat absorbed by ice slurry on melting makes it an attractive choice for achieving high degree of cooling. The numerical analysis was conducted by simulating the ice slurry tube flow region and air flow region of tube–fin heat exchanger in the air-handling unit of HVAC system. For the simulation six different louver patterns with 10 to 55 louver angle were considered. The design of the tube–fin heat exchanger for optimal heat transfer and pressure drop characteristics was also determined with the optimization parameter like louver angle, fin pitch, and ice slurry flow velocity.