Cold Storage System Research Articles

Cold-to-electricity conversion using a piston based engine in cold energy storage (CES) system, part two: An experimental study

This study concerns the practical power tests in a piston based engine with a new valve scheme. By developing the controlling method, the injection of expansion gas into the engine cylinder can be flexibly controlled in terms of requirements under different conditions. The effects of motor speed, p-crank angle, gas pressure and temperature and the category of the expansion gas were all investigated. With increasing of the motor speed, gas pressure or temperature, power generation by the piston-based engine increases. However, the power generation was restrained due to the limited volume flow rate caused by the minimum internal diameter of the valves. The optimal p-crank angle was found in the range of 55°–76° for obtaining the maximum power generation under certain conditions. In practical engine system, the p-crank angle was normally set below 60° for diminishing the gas resistance in the engine cylinder. The experimental results shows that the net electricity consumption is induced due to the block of the exhaust gas in the cylinder. However, by improving the limit value of flow rate at the engine inlet, the engine performance was significantly improved, leading to an overall electricity output by the engine system. This shows the value of the piston-based engine in the CES system.

Phase equilibrium and formation behaviour of CO2-TBAB semi-clathrate hydrate at low pressures for cold storage air conditioning applications

Cold thermal storage has been widely used in air conditioning systems. For electric air conditioning, it helps to shift the peak load on electricity grids; for solar cooling, it enables cooling supply during solar outages. CO2 hydrate has been proposed as a cold storage medium for its suitable phase change temperature and large latent heat. Tetra-n-butyl ammonium bromide (TBAB) has been studied to moderate the formation pressure of CO2 hydrate. In this study, formation and dissociation of CO2-TBAB semi-clathrate hydrate were conducted at low pressures (<10bar) applicable to the operating conditions of air conditioning systems. The hydrates were formed with the TBAB mass fraction of 10, 20 and 32wt%. Using the T-history method, the formation enthalpy of CO2-TBAB semi-clathrate hydrate was measured in a self-fabricated reaction tube. In addition, the formation behaviour of CO2-TBAB semi-clathrate hydrate, namely the CO2 gas uptake, the induction time and the supercooling degree, were investigated under various feed pressures and heat transfer fluid (HTF) temperatures. Besides, secondary promoters (tetra-n-butylammonium fluoride (TBAF) at the mass fraction of 0.1, 0.5, 2.0 and 3.5wt%, sodium dodecyl sulphate (SDS) at the mass fraction of 0.1, 0.3 and 0.5wt%, and TiO2 nanoparticle in 20 and 80nm) were used to aid the hydrate formation. The aim of this study is to reduce the capital and operating cost of a CO2 hydrate cold storage system by increasing the gas uptake, decreasing the supercooling degree and shortening the induction time.

Night sky cooling for concentrating solar power plants

Concentrating solar power (CSP) plants are currently designed with either cooling towers or air-cooled condensers. These two alternatives have a trade off: cooling tower evaporative cooling systems use water, which is a scarce resource in the desert environments where CSP is implemented, but air-cooling results in decreased power plant performance. In this paper, a radiation-enhanced cooling system for thermal power plants is analyzed with a detailed heat transfer model and shown to be feasible for CSP. The proposed system consumes no water and has the potential to out-perform air-cooling. Heat transfer occurs by convection and radiation to the cold night temperatures of desert environments. The radiators are uncovered black panels with tubes of cooling fluid circulated to a cold storage system. The radiators’ performance is modeled using a two-dimensional finite difference model and the complete power plant system is modeled on an hourly basis using a standard power plant with thermal energy storage. If the night sky cooling system is the same size as the solar collector field, annual simulation shows that the system can provide over 90% of the required cooling. In addition, performance is improved compared to traditional air-cooling because the parasitic load for circulating water in the radiator system is about 1% of gross energy production while the parasitic load for an air-cooled power plant is about 4%. The night sky cooling system is a potential solution to the water issues that face CSP power plants and other power plants located in desert environments.

Cold-to-electricity conversion using a piston based engine in cold energy storage (CES) system, part one: A theoretical study

This study concerns the cold-to-electricity conversion in a piston based engine. A theoretical model was developed to predict the power generation rate in the engine. Parametric study showed the significant effect of p-crank angle, motor speed, gas pressure and temperature and chamber volume on the power generation by the piston based engine. It was found that optimal p-crank angle was normally in the range of 55°∼76°. The minimum inner diameter of the valves connected to the engine was a crucial factor that limited the power capacity of the engine system. Based on the experimental data, the large engine (1900 cm3) and small engine (162 cm3) had an actual efficiency of 24.1% and −23.6%, respectively. This implied that the large engine was feasible to be used in CES system for electricity re-generation during peak hours. However, the induced CES efficiency was 18.9% and 52.1% in two different situations. The results indicate the importance of engine development in promoting the CES technology.

Investment analysis of Hungarian apple-orchard and fruit storage projects

There are profound, long-term changes in world apple production and trade. The former hegemony of Europe in apple production doest not exists any more, among the most important apple exporters the emerging economies have a growing importance. The globalising apple market means new challenges of traditional producers. This is especially true for Hungary, which has been the most important apple exporter in terms of quantity thirty years ago, but now its production hardly covers the domestic demand. A necessary precondition of the modernisation is the re-construction of plantations and the cold-storage system. Analysing the economic effi ciency of apple production and cold storage, it is obvious, that a necessary precondition for the modern, competitive apple production is the availability of cold-storage facilities. Neither the apple-production, nor the cold-storage can not evaluated separately from each other. Under current Hungarian conditions there is a need for active state support for the establishment of cold-storage facilities.

EFFECT OF COLD STORAGE USING SOLAR ENERGY ON QUAILTY OF POMEGRANATE FRUITS

This study aims to evaluate a cold storage system using solar energy of pomegranate fruits (cv. Wonderful) for storage period 50 days under storing temperatures of (5 oC) and relative humidity of 90 -95 %. The storage process was done using two refrigeration systems one of them is a refrigerator driven by solar energy, the other one driven using electrical energy. The component of refrigerator driven by solar energy consists, two parallel photovoltaic cells (PV), two batteries, an inverter, and cables, In addition to refrigerator unit. Testing the PV system showed that, nine hours discharge time for one battery is available during connected to the cold storage. So it is necessary to use two batteries connected in series to be suitable for refrigerator driven power and Egyptian conditions, and can therefore run the cooling system throughout the day without interruption. The percentage of weight loss, hardness, and total soluble solid (TSS) for pomegranate fruits using refrigerator driven using photovoltaic cell were 8.46 %, 11.18 kgf, and 15.80% respectively; Meanwhile cold storage driven by electrical energy, these parameters were 8.79 %, 10.41 kgf, and 15.71% respectively. Operating cost using solar energy achieved the lowest cost compare with using electrical energy, therefore, can rely on the use of solar energy instead of electrical energy to operate the refrigeration unit. From the above results, pomegranate fruit inside PV driven refrigerator has a good quality compared with pomegranate fruit inside electrically driven refrigerator.

Optimal design and application of a compound cold storage system combining seasonal ice storage and chilled water storage

Seasonal cold storage using natural cold sources for cooling is a sustainable cooling technique. However, this technique suffers from limitations such as large storage space and poor reliability. Combining seasonal storage with short-term storage might be a promising solution while it is not explored sufficiently. This paper presents a compound cold storage system that combines a heat pipe-based seasonal ice storage system with a chilled water storage system. The seasonal ice storage system automatically charges winter cold energy in the form of ice. In summer, the stored ice is extracted for cooling, and then the melting ice is used as a chilling medium for chilled water storage. Design optimization of the seasonal ice storage system and the compound storage system is addressed, including the sizes of heat pipes, the configuration and volume of the cold storage tank and the chiller capacity. A case study is conducted to demonstrate the design and the application of the proposed system in a real building in Beijing. Results show that the appropriate combination of the two types of cold storage can greatly improve the applicability of the seasonal cold storage and reduce the life-cycle cost of a building cooling system by 40%.

A new solar based multigeneration system with hot and cold thermal storages and hydrogen production

A multigeneration system based on solar thermal energy associated with hot and cold thermal storage is designed and analyzed energetically and exergetically. The system produces electricity, a heating effect, a cooling effect, hydrogen, and dry sawdust biomass as outputs by means of organic Rankine cycles, a heat pump, two absorption chillers, an electrolyser, and a belt dryer. The intermittent behavior of the renewable energy source is addressed through the incorporation of hot and cold thermal storage systems to operate an organic Rankine cycle and provide cooling at night. The performance assessment indicates that the overall (day and night) energy and exergy efficiencies are 20.7% and 13.7%, respectively. The majority of the total exergy destruction is attributable to the sawdust belt dryer, at about 64.0%.

공회전 제한장치 차량에서 냉방 성능 유지를 위한 축냉 시스템 적용에 대한 연구

This study explores the feasibility of a cold storage system to provide thermal comfort for idle stop and go (ISG) vehicles. ISG function is the most valuable and environmental friendly technology in the current automobile industry. However, when an ISG vehicle stops, meaning when the engine standstill, the air-conditioning system does not work, because the compressor also stops. Therefore, passenger thermal comfort is not maintained, as cold air is not provided in the cabin. Consequently, many automakers have studied electric air-conditioning systems based on electrically-driven compressors or cold storage systems using phase-change materials. The experiments herein were conducted for the feasibility testing of different types of cold storage heat-exchangers, cold storage mediums, and thermo-expansion valves with current air-conditioners. The auxiliary cold storage system, filled with phase-change materials, was located behind the evaporator and almost stacked on top of it. In the experimental results, the air discharge temperature rate of increase was better than the conventional air-conditioning system when the compressor stopped and thermal comfort was maintained with <TEX>$1.9{\sim}4.3^{\circ}C$</TEX> decreases within 60 seconds. The #1 cold storage heat-exchanger (CSH), #2 thermo-expansion valve (TXV) and #2 phase change material (PCM) were chosen because of the best temperature rise delay. It was concluded that a cold storage system is an effective solution for ISG vehicles to maintain thermal comfort during short engine stops.

Respiration behaviour and heat of respiration of mango (cv. Langdo) under different storage conditions

Individual agricultural commodity has substantial rate of respiration which varies from commodity to commodity and cultivar to cultivar. Quantification of rate of respiration and thereby heat generated due to respiration is require to develop controlled, modified or cold storage system and to predict the shelf life. A scientific study was carried out to determine the effect of different storage conditions on rate of respiration and heat of respiration of mango fruits (cv. Langdo). Air tight multi-chamber temperature and RH control system was developed to conduct the experiment at various temperatures. Mango fruits were stored at 10, 15, 20, 25°C and ambient temperature in the developed air tight multi-chamber system. Rate of respiration and heat of respiration was determined for different storage conditions. At the beginning maximum rate of respiration, 61.44, 71.76, 80.03, 83.93, 100.42 mlCO2/kg/h and heat of respiration, 7164.84, 8221.14, 9009.34, 9287.19, 10745.55 kcal/metric ton/day was observed at 10, 15, 20, 25°C and ambient temperature respectively. It was found that under steady state storage condition the rate of respiration and heat of respiration was increased with increase in temperature whereas decreased with time for all storage conditions.

Numerical Analysis of Cold Storage System with Array of Solid-Liquid Phase Change Module

This paper is the fundamental study for the application of cold storage system to the transportation equipment by sea and land. This numerical study presents the solid-liquid phase change phenomenon of calcium chloride solution of 30wt %. The governing equations are 1-dimensional unsteady state heat transfer equations of order partial differential equations. This type of latent heat storage material is often usable in fishery vessel for controlling the temperature of container with constant condition. The governing equation was discretized with finite difference method and the program was composed with Mathcad program. The main parameters of this solution were the initial temperature of heat storage material, ambient temperature of cold air and the velocity of cold air. The data of boundary layer thickness becomes thin with the increasing of cold air flowing velocity and also the heat storage completion time become shorten.

Nanofluids: An innovative phase change material for cold storage systems?

An analytical approach is used to solve a contact melting problem where an alumina-water nanofluid is used as the phase change material. The mathematical model describing the process is reduced to three ordinary differential equations which are solved by means of the Heat Balance Integral Method. The melt front separating the solid and liquid constituents that possess different thermophysical problems (dependent on nanoparticle volume fraction) is tracked. The liquid height, solid height, total melt and melt rates are determined, as well as times to the onset of melting and melt completion. The results for both base fluid and nanofluid are compared, showing that the nanofluid phase change material may not be more efficient at releasing energy and that the efficiency is dependent on system size.

Modelling and experimental validation of a fluidized bed based CO2 hydrate cold storage system

Latent heat thermal storage (LHTS) systems can be applied to minimize the discrepancy between energy supply and demand in cold applications. Combining this system with night time generation of CO2 hydrate slurry can significantly reduce the investment costs for cooling purposes. These systems require hydrate generation temperatures around 8°C and can, from an energetic point of view, contribute to significant energy savings. In this paper a numerical and experimental investigation is carried out for a shell-and-tube fluidized bed heat exchanger, combined with a hydrate slurry storage vessel. When required, heat can be removed from the storage by circulating the slurry through a heat exchanger which is part of the cold distribution system. The model of the fluidized bed heat exchanger is coupled with the model of the cold storage system. The phase change process is modelled by using a crystal growth model. The presented work provides experimental data for the thermal performance and hydrate generation of a fluidized bed based LHTS system for a CO2 hydrate cold storage system.

The Effects of Direct Oxygen Supply During Static Cold Preservation of Rat Livers: An Experimental Study.

We aimed to determine the biochemical and histopathologic effects of direct oxygen supply to the preservation fluid of static cold storage system with a simple method on rat livers. Sixteen rats were randomly divided into 2 groups: the control group, which contained Ringer's lactate as preservation fluid; and the oxygen group, which contained oxygen and Ringer's lactate for preservation. Each liver was placed in a bag containing 50 mL Ringer's lactate and placed in ice-filled storage containers. One hundred percent oxygen supplies were given via a simple, inexpensive system created in our laboratory, to the livers in oxygen group. We obtained samples for histopathologic evaluation in the 12th hour. In addition, 3 mL of preservation fluid was subjected to biochemical analysis at 0, sixth, and twelfth hours. Aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and pH levels were measured from the preservation fluid. In oxygen-supplemented group, the acceleration speed of increase in alanine aminotransferase and lactate dehydrogenase levels at sixth hour and lactate dehydrogenase, alanine aminotransferase, and lactate dehydrogenase levels at 12th hour were statistically significantly reduced. In histopathologic examination, all parameters except ballooning were statistically significantly better in the oxygen-supplemented group. This simple system for oxygenation of liver tissues during static cold storage was shown to be effective with good results in biochemical and histopathologic assessments. Because this is a simple, inexpensive, and easily available method, larger studies are warranted to evaluate its effects (especially in humans).

Experimental and numerical investigation of form-stable dodecane/hydrophobic fumed silica composite phase change materials for cold energy storage

A kind of form-stable composite phase change materials used for cold thermal energy storage is prepared by absorbing dodecane into the hydrophobic fumed silica. With relatively suitable pore diameter and hydrophobic groups, hydrophobic fumed silica is beneficial to the penetration and infiltration of dodecane and the leakage problem solving. Scanned by electron micrographs and Fourier transformation infrared, the composite phase change material is characterized to be just physical penetration. Besides, the differential scanning calorimeter and thermo gravimetric analysis reveals the high enthalpy, good thermal stability and cycling performance of this composite phase change material. What’s more, Hot-Disk thermal constants analyzer demonstrates that the composite phase change material has low thermal conductivity which is desired in cold storage application. In the experiment, a cold energy storage system is set up and the results from the experiment show that the system has excellent performance of cold storage by incorporating composite phase change material. Apart from that, the experimental data is found to have a great agreement with the numerical simulation which is carried out by using the commercial computational fluid dynamics software FLUENT.

Thermal efficiency analysis of the cascaded latent heat/cold storage with multi-stage heat engine model

The cascaded thermal storage technique has emerged as an important solution for efficient conversion and utilization of thermal energies. In this paper, an exergy optimization was performed for cascaded latent cold/heat storage using multi-stage heat engine model. The optimization solution for both heat storage and cold storage systems was obtained, which was used for guiding the selection of PCMs with two examples presented. Cascaded thermal storage with increased stage number can not only extend temperature band for multi-grade thermal energy, but also reduce the exergy of the outlet HTF. It was found that heat transfer enhancement (improving NTU) is very necessary for a cascaded thermal storage system. The COP of cold energy may be greater than 1, which is also higher than that of heat for the same temperature difference in a cascaded thermal storage system. The increased environment temperature improves the COP of the cascaded cold storage (from 0.54 to 0.68) but reduces that of the cascaded heat storage (from 0.42 to 0.366). In the practical design of the cascaded thermal storage system, the stage number should be determined by balancing economics and system complexity.

A seasonal cold storage system based on separate type heat pipe for sustainable building cooling

Seasonal cold storage is a high-efficient and environmental-friendly technique that uses the stored natural cold energy in winter (e.g., snow, ice or cold ambient air) for free-cooling in summer. This paper presents a seasonal cold storage system that uses separate type heat pipes to charge the cold energy from ambient air in winter automatically, without consuming any energy. The charged cold energy is stored in the form of ice in an insulated tank and is extracted as chilled water for cooling supply in summer, which help to reduce the chiller running time and reduce the associated electricity consumption and greenhouse gas emission significantly. A quasi-steady two-dimensional mathematical model of the system is developed for characterizing the dynamic performance of ice growth (i.e., cold charging). The model is validated using the field measurement data from an ice charging experiment conducted in Beijing. The impacts of various affecting factors, including the weather data and the key parameters of heat pipes, on the charging performance of the cold storage system are analyzed. The effectiveness and sustainability of the proposed system for cooling are demonstrated through a case study of a kindergarten building in Beijing.

A research on a following day load simulation method based on weather forecast parameters

Accurate simulation and forecast of cooling load is vital in the design of efficient cooling in a cold storage system. In order to be more accurate in predictions and reduce simulation errors, most of previous studies have focused on how to improve the methodology of load forecast or how to correct the annual meteorological parameters library in face of global warming. Although such approaches can improve the accuracy of load forecast, they still have major weaknesses, such as their requirement of large amount of daily or hourly historical load records and their failure to predict weather data for any given day accounting for future change in the macro climate. To address these problems, a following day load simulation method (FDLS) is proposed by the authors in this research. This method simulates the cooling load based on weather forecast parameters published by meteorological authorities. The accuracy of FDLS is validated by comparing the simulation results with the actual data collected from a cold storage building. Furthermore, the advantages and disadvantages of the FDLS method are highlighted in this study.

축냉 시스템이 차 실내 열 쾌적성에 미치는 영향에 관한 실험적 연구

Abstract : This paper presents the experimental study of cabin thermal comfort using a cold storage heat exchanger in a vehicle air-conditioning system. Recent vehicle-applied ISG functions for fuel economy and emission, but when vehicles stop, compressors in the air-conditioning system stop, and the cabin temperature sharply increases, making passengers feel thermal discomfort. This study conducts thermal comfort evaluation in the vehicle, which is applied to a cold storage system for the climate control wind tunnel test and the vehicle fleet road test with various airflow volume rates and ambient temperatures blowing to the cold storage heat exchanger. The experimental results, in the cold storage system, air discharge temperature is 3.1-4.2°C lower than current air-conditioning system when the compressor stops and provides cold air for at least 38 extra seconds. In addition, the blowing airflow volume to the cold storage heat exchanger with various ambient temperature was examined for the control logic of the cold storage system, and in the results, the airflow volume rate is dominant over the outside temperature. For this study, a cold storage system is economically useful to keep the cabin at a thermally comfortable level during the short period when the engine stops in ISG vehicles.

Where the problem is with Listeria monocytogenes ?

Foodborne diseases are considerate an important public health concern in many countries and each year, ingestion of foods contaminated with pathogens causes millions of episodes of diarrhea and other debilitating effects. As results, large number of hospitalizations and thousands of deaths occur, and billions of Euros and Dollars are spent every year with recalls and patients medical treatment. The emergence of some of these diseases is the result of complex interactions, such as the advances in the medical field, the expansion of the food industry, cold storage systems, as well as the change in eating habits. Since the consumption of contaminated food has been associated with the development of diseases, various studies were developed, especially in industrialized countries, in order to clarify the relationship between these pathogens and their persistence in the food processing environment, their main routes of contamination, how they can survive and multiply in foods, and their potential to cause disease. Among these microorganisms, Listeria monocytogenes is a concern for Public Health agencies. Several countries adopt a zero tolerance policy regarding the presence of L. monocytogenes in foods. However, the environment conditions of food processing industries were always partially located in secondary importance in the tracking presence of reservoirs for L. monocytogenes and other foodborne pathogens. In recent years, phenotypic and genotypic studies led to new insights into ecology, epidemiology, virulence potential and genetic evolution of various genuses of bacteria. L. monocytogenes is the causative agent of listeriosis, a severe foodborne disease that affects mainly the elderly, immunocompromised individuals, pregnant women and neonates. Listeriosis is characterised by gastroenteritis and septicaemia, leading to abortion and infections in the nervous system. Its mortality rate varies from 20 to 30%, this being common mainly when the pathogen is able to cause encephalitis and meningitis.