Ice Slurry Generation Research Articles

Performance of Ice Slurry Generator with Mechanical Scraper using R-22 and R-290

Performance of Ice Slurry Generator with Mechanical Scraper using R-22 and R-290

Impacts on the solidification of water on plate surface for cold energy storage using ice slurry

Ice slurry has been widely used for thermal energy storage system due to its high cold energy storage capacity. To effectively improve the efficiency of ice slurry generator, it is essential to have a deeper understanding about the solidification mechanism on the plate surface of ice generator, which is affected by many factors, such as the roughness of surface and the apparent contact angle. This work studies the impacts of roughness and inhibitor concentration on the freezing temperature, subcooling and the heterogeneous nucleation energy at the surface of aluminum, copper and Teflon plates. Results show that both the roughness and the inhibitor concentration can clearly affect the freezing temperature of water droplet and the heterogeneous nucleation energy. In general, the freezing temperature rises and the subcooling and the heterogeneous nucleation energy drop as the surface roughness increases for all studied materials; and the heterogeneous nucleation energy also increases with the increase of inhibitor concentration. Since the heterogeneous nucleation energy is mainly determined by the substance and the roughness, while not by the surface material, it is important to increase the roughness in order to reduce subcooling and save energy, especially for copper and aluminum.

Experimental study on the characteristics of ethanol solution’s vacuum flash under adsorption condition

Characteristics of ethanol solution’s vacuum flash under adsorption condition were investigated experimentally. The temperature of cooling medium, ethanol solution flow velocity, and ethanol solution concentration were varied as experimental parameters. Explore the effects of these parameters on ice making process via controlling a single parameter. As results showed, adsorption condition can effectively reduce the peak pressure of ice slurry generator at initial flash moment. This peak pressure just reaches the minimum (800Pa) when the cooling medium temperature in adsorption chamber is at 30°C. The larger ethanol solution velocity of flow, the higher pressure when the whole system is stable in the same ethanol solution concentration. When the ethanol solution flow rate (velocity of flow) is at 5L/h, the ethanol solution temperature can be reduced to −9°C, which is more conducive to the production of ice crystals, but it may have ice blocking phenomenon. Ethanol additives can promote the solution to cool the temperature below 0°C, and the higher the concentration is, the lower the temperature is. But for this ice preparation system, when the solution concentration is at 5%, it is more favorable to produce ice crystals. Through the analysis of all experimental conditions, 10L/h of ethanol solution flow rate with ethanol concentration of 5% is the best ice production condition under the adsorption conditions.

Ice Slurry Generation for Direct Contact Cooling

Ice slurry has attracted a great deal of attention as a coolant for direct contact cooling. In this study, we generated ice slurry by the method of pressure shift freezing (PSF), which is based on the freezing-point depression of an aqueous solution at high-pressure conditions. As a result, the basic characteristics of the ice slurry generation are clarified. Moreover, the physical properties of the ice slurry indicate that the shape of an ice particle in the ice slurry is strongly affected by both the supercooling degree and the aqueous solution concentration.

Experimental study on crystallization process and prediction for the latent heat of ice slurry generation based sodium chloride solution

The research on the crystallization process is a fundamental task for the investigation of freezing properties of ice slurry. This paper presents an experimental study on the influence of concentration on essential parameters of the crystallization process for the ice slurry produced from sodium chloride solution using a scraped surface heat exchanger. It was found that the liquid temperature experiences four different segments during the whole crystallization process. This trend keeps accordance with the result from literature and it was used to verify the accuracy of the experiment test. It was also observed that the concentrations of sodium chloride solution have significant effects on several freezing properties of the ice slurry generation. The curves obtained in this paper are useful to predict the freezing point and the solidification time in practice. Additionally, a mathematical correlation between the latent heat and concentration was developed eventually by polynomial fitting the curve gained from experiments. The error between the fitting curves and original experimental data was no more than 5%. Totally, during the ice generation process, it is of great significance that the concentration of brine solution can be adjusted to meet the cooling capacity requirement according to the fitting curves and mathematical correlations obtained in this paper.

Experimental Study on Crystallization Process and Freezing Properties of Ice Slurry Generation Based Sodium Chloride Solution

Abstract The crystallization process of ice slurry plays an important role in the cooling capacity and other freezing properties of the new-type cool agent. An experimental study on the important parameters during the crystallization process of ice slurry has been carried out and reported in the paper.The ice slurry is produced from sodium chloride solution using a scraper. It has been found that the liquid's temperature experiences four stages during the crystallization process. This variation trend keeps accordance with literatures’ results, which verifies the responsibility of the test. It has also been investigated that the concentrations of sodium chloride solution have effects on several freezing properties of the ice slurry generation. In addition, a mathematical correlation between the latent heat and concentration has been developed eventually by polynomial fit. The error between the fitting curves and original experimental data is less than 10%. Overall the correlations and curves obtained in this paper can be used to predict the freezing point and the solidification time practically. It is of great significance that the concentration of brine water used for making ice can be estimated and controlled to meet the cooling capacity requirement.

A Review Paper of Sea-Water Ice Slurry Generator and its Application on Indonesian Traditional Fishing

Sea-water ice slurry generator is aimed to produce ice-slurry using sea-water while fishing on boat. Some models of ice slurry generator have been researched and developed. Indonesia as an archipelago and maritime nation has big potential in fishery. Appropriate model for Indonesian traditional fishing boat is necessary. The most important part of ice slurry generator is evaporator, including auger and scrapper. Some studies on ice slurry are presented in this review paper in order to get larger view on design of ice slurry generator.

Analysis of ice slurry production by direct contact heat transfer of air and water solution

In this paper, a novel system using direct contact heat transfer between air and water solution was proposed to generate ice slurry. The heat transfer process and the system performance were studied; energy efficiency coefficients of 0.038, 0.053, and 0.064 were obtained using different solutions. An empirical relationship between the volumetric heat transfer coefficient U v and the main parameters was obtained by fitting the experimental data. The U v calculated from the empirical formula agreed with the experimental U v quite well with a relative error of less than 15%. Based on the empirical formula, a laboratory-scale direct contact ice slurry generator was then constructed, with practical application in mind. If the air flow rate is fixed at 200 m3/h, the ice production rate will be 0.091 kg/min. The experimental results also showed that the cold energy consumption of the air compressor accounted for more than half of the total amount. To improve the system energy efficiency coefficient, it is necessary to increase the air pipes insulation and the solution’s thermal capacity, and also it is appropriate to utilize the free cold energy of liquefied natural gas (LNG).

Characteristics of Sea-Water Ice Slurry for Cooling of Fish

A more effective of cooling method is necessary for fish storage to get high quality and long freshness of fish. Ice block is not sufficient for fish storage because of its hard-solid surface that can damage the fish. Moreover for some remote area it is difficult to find ice block in good time with reasonable/low price. One solution for this problem is the using of sea-water ice slurry for fish cooling. Ice slurry is formed when the sea-water temperature goes down to its freezing point, when the early nucleation is formed. Crystal ice can be formed when chemical equilibrium is occurred. The purpose of this present study is to observe the characteristics of ice slurry generation using scraper blade evaporator and orbital rod evaporator. The experiment is done under some experimental conditions.

STUDY ON NEW ICE SLURRY GENERATOR USING NaCl AQUEOUS SOLUTION AT LOW CONCENTRATION

A cold thermal energy storage system has been developed for HVAC. There are many ice-based cooling systems operating around the world. Ice slurry, which is a mixture of fine ice crystals and liquid water, is utilized in ice storage systems owing to its good flowability and large latent heat of fusion. For slurry ice production techniques, there are presently a number of commercially available ice slurry generators (e.g., Supercooled slurry ice generator, Scraper type generator, and Vacuum type generator, etc.). In the present study, a new method was developed to generate ice slurry without the deposition of an ice layer on a cooled surface. The basic components of the experimental apparatus is a cooling brine circulating loop, a high pressure pump, a valve, an aqueous solution flow loop containing the test section, which is made of transparent acrylic, and the associated instrumentation. This new method is based on freezing-point depression of the aqueous solution, which is maintained under high-pressure conditions. To control the timing for solidification and to generate ice slurry, we investigated the relationships among the pressure and temperature of the aqueous solution. The freezing phenomenon of the aqueous solution in the test section was observed in detail. As a result, we developed a new ice slurry generator based on the new method that controls the pressure and temperature of the aqueous solution. Experimental results showed that the characteristics of the ice slurry generation were closely related to the pressure and initial stage temperature of the test fluid. Finally, the optimum operation condition of the ice slurry generator based on visualization experiment was discussed.

Ice slurry generator using freezing-point depression by pressurization – Case of low-concentration NaCl aqueous solution

Ice slurry, which is a mixture of fine ice crystals and liquid water, is utilized in ice storage systems owing to its good flowability and large latent heat of fusion. In the present study, a method was developed to generate ice slurry without the deposition of an ice layer on a cooled surface. This method is based on freezing-point depression of the aqueous solution, which is maintained under highpressure conditions. To control the timing for solidification and to generate ice slurry, we investigated the relationships among the pressure, temperature, and concentration of the aqueous solutions. We developed an ice slurry generator based on the new method that controls the pressure and temperature of the aqueous solution. Experimental results showed that the characteristics of the ice slurry generation were closely related to the pressure and initial stage temperature of the test fluid.

Review of Recent Patents on Ice Slurry Generation

Ice slurry can be employed with advantages in many fields, including refrigeration, air conditioning, supermarket display, food process and mine cooling and so on. The most important issue concerning the ice slurry application is still its generation method, relating to the efficiency and reliability of water or aqueous solution converting to ice crystals or ice slurry. Though the ice slurry generation methods have been widely investigated, patented and employed, recent patents of ice slurry generation methods after the year of 2000 are reviewed in this article, which is mainly focused on the generation efficiency and reliability. The novel promotions on the already disclosed methods, including the scraped surface generator, the supercooling method, the direct contact generation, the vacuum ice slurry generator are introduced, expecting to provide more inspirations for the designers. Keywords: Ice slurry, generation methods, refrigeration system, scraped surface generator, blade, auger, supercooling method, supercooling release, direct contact heat exchange, primary refrigerant, secondary refrigerant, vacuum ice slurry generator, absorption, slurry generator combined with storage, recent patent, mine cooling, fraction

Heat transfer performance of a newly developed ice slurry generator: A comparative study

An advanced super-cooling type heat exchanger is presented as an ice slurry generator. It reduces investment costs and it can be operated with high heat transfer rates and at less power consumption compared with traditional heat exchangers of super-cooling type of shell and tube design, and of scraped surface type, which are commonly used up to now. The different ice slurry generation methods were reviewed. A super-cooling ice slurry generator type was experimentally tested and compared with a traditional scraped surface type. Some interesting advantages were observed in case of super-cooling type, developed in this paper. The stable operating range was slightly smaller compared with the traditional scraped surface type, and heat transfer coefficients were somewhat smaller due to smaller amount of generated ice fraction as common super-cooling type. It is supposed that higher velocity of the super-cooled water jets than reported will lead to increase the produced ice concentration.

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.

Performance improvement of vertical ice slurry generator by using bubbling device

For the dynamic ice making system, a long outstanding problem is how to make ice continuously without adhesion to the cooling wall. In this paper, a bubbling device was applied to an experimental dynamic ice making system to suppress ice adhesion to the cooling wall. The experimental dynamic ice making system employed an air compressor to create air bubbles, and for the sake of this purpose, its ice slurry generator was set up vertically. To achieve an optimum working condition, a performance study on this system was conducted. The effects of the air blowing rate and other operating parameters on the performance were experimentally studied. It is concluded that the air bubbles are effective to suppress ice adhesion to the cooling wall; however, the air blowing rate of the air compressor should be optimized.

Ice slurry generation involving moving parts

Efficient ice slurry generation systems continuously produce ice crystals of desired size offering high cooling rates without any wall freeze-up. Although several ice slurry generation technologies have been and are being developed, currently only the scraped surface and supercooling type have been widely used in commercial applications. Typical ice slurry generators require the use of mechanical devices such as scraper blades, orbital rods or impacting solid particles to maintain a freeze-free ice-generating surface and achieve a continuous ice slurry production. The basic principles, operating ranges and heat transfer characteristics of the scraped surface and fluidized bed type ice slurry generators are reviewed. From this review it became clear that the basic crystallization principles and heat transfer mechanisms in current ice generators are not yet fully understood. To elucidate the heat transfer mechanisms, heat transfer measurements are presented in a prototype compact ice generator.

From physical properties of ice slurries to industrial ice slurry applications

The use of ice slurries dates back many millenniums, e.g. the ancient Romans applied the cooling of snow-water and ice-water mixtures. Approximately two decades ago a breakthrough of the new technology of producing ice slurries has set in the refrigeration domain for the cooling of shops and supermarkets. After some difficulties at the beginning, it is now possible to build systems, which operate as designed. However, there is still a huge potential to lower the energy consumption and the costs of the systems. Actions in this direction are the design of new ice slurry generators, the development of new concepts for storage and mixing, etc. In this article a short review of the basic research on ice slurries is presented. Furthermore, practical problems of the application of the technology in refrigeration and process techniques are discussed.

The control of ice slurry systems: an overview

This article outlines some typical control strategies for the basic components of an ice slurry system. From this review it became apparent that the control of terminal units is not fundamentally different from the control of classical single-phase secondary cooling systems, except from the fact that it must be based on the use of local pumps and the ON–OFF operation of actuators to avoid ice plugging problems. The safe control of the ice generator can be ensured with a simple thermostat, although the resulting ice concentration control would be approximate. It was also demonstrated that any ice accumulation in the storage tank would not prevent the ice slurry system from functioning safely. As a final precaution, it was not recommended to operate an ice slurry generator at low solute concentrations and temperatures greater than −3/−4 °C due to the risk of plugging up the distribution loop and causing mechanical wear to the ice generator.

Ice-slurry production using direct contact heat transfer

An ice slurry generation system was developed using direct contact heat transfer between water and the coolant, Fluroinert FC-84. The location of the coolant nozzle is an important design consideration to avoid clogging due to freezing of water. An ice fraction of up to about 40 percent was obtained with the nozzle located at the bottom of the ice slurry tank and the jet directed upwards into the water. Two simplified model were developed to extract the heat transfer coefficient between the coolant drops and the water. The first model requires as input the average drop diameter and the residence time while the second model uses the measured drop diameter distribution. The estimated heat transfer coefficients are much smaller than those computed using single-sphere correlations.

Validation of the use of heat transfer models in liquid/solid fluidized beds for ice slurry generation

Heat transfer coefficients in a liquid/solid fluidized bed heat exchanger are investigated for application in ice slurry generators. A range of temperature driving forces is determined in which ice slurry generation is stable. In this range ice crystal formation or growth does not affect heat transfer coefficients. A model is proposed that accurately predicts heat transfer coefficients in the fluidized bed ice slurry generator. Due to lower temperatures and higher viscosity in ice slurry generation, heat transfer coefficients measured are lower than predicted with heat transfer correlations specific for liquid/solid fluidized bed heat exchangers. Heat transfer coefficients measured are however significantly higher than for single phase fluid flow.