Cold Accumulator Research Articles

Energy Efficiency of the Heat and Power Complex for Highly Efficient Use of the Secondary and Renewable Energy Resources

The article describes a heat and power complex utilizing internal sources of consumer heat, as well as using renewable energy sources. The power complex also includes heat accumulators, cold accumulators and a cascade heat pump plant. This heat pump plant has a high conversion factor of electrical energy due to optimization of heat flows. In this article, a method for determining the energy efficiency of the heat-energy complex under consideration is disclosed.

Study of Cycling Air-Cooling System with a Cold Accumulator for Micro Gas-Turbine Installations

Using the cycling air-cooling systems of the CTIC type (Combustion Turbine Inlet Cooling) with a cold accumulator in a micro gas-turbine installation (micro-GTI) to preserve its capacity under the seasonal temperature rise of outside air is described. Water ice is used as the body-storage in the accumulators, and ice water (water at 0.5–1.0°C) is used as the body that cools air. The ice water circulates between the accumulator and the air-water heat exchanger. The cold accumulator model with renewable ice resources is considered. The model contains the heat-exchanging tube lattice-evaporator covered with ice. The lattice is cross-flowed with water. The criterion heat exchange equation that describes the process in the cold accumulator under consideration is presented. The calculations of duration of its active operation were performed. The dependence of cold accumulator service life on water circulation rate was evaluated. The adequacy of the design model was confirmed experimentally in the mock-up of the cold accumulator with a refrigerating machine periodically creating a 200 kg ice reserve in the reservoir-storage. The design model makes it possible to determine the weight of ice reserve of the discharged cold accumulator for cooling the cycle air in the operation of a C-30 type micro- GTI produced by the Capstone Company or micro-GTIs of other capacities. Recommendations for increasing the working capacity of cold accumulators of CTIC-systems of a micro-GTI were made.

Н2О – Nа2S2О3∙5Н2О жүйесінде эвтектикалық құрамның кристалдануының термодинамикалық параметрлерін талдау

При разработке холодоаккумуляторов на основе фазовых переходов (ХА ФП) в настоящее время основные усилия направлены на расчет различных конструкционных устройств и таких параметров, как объем, площадь поверхности ХА, коэффициент теплопередачи (или термическое сопротивление) на границе холодоаккумулирующего материала (ХАМ) с материалом аккумулятора, температура и время зарядки и разрядки, энергетический КПД. Вместе с тем, слабо освещается физическая и химическая проблемы учета процессов самих фазовых переходов и их влияние на эффективную работу ХА. В данной работе по экспериментально полученным термограммам проведен анализ кинетических и термодинамических параметров плавления и кристаллизации эвтектического состава в системе Н2О – Nа2S2О3∙5Н2О (ТСН-5), который можно использовать как ХАМ, работающий при Т=262±1 К (-11±1°С). Выявлено, что в зависимости от величины прогрева жидкой фазы относительно температуры плавления и дальнейшего охлаждения имеют место два вида кристаллизации. Первый вид – это квазиравновесная кристаллизация (КРК), которая происходит при температуре , совпадающей с температурой ТL = TE. Второй вид является неравновесно-взрывной кристаллизацией (НРВК), которая начинается после достижения определенных предкристаллизационных переохлаждений . Были рассчитаны активности , , коэффициенты активностей , и энергии активации , в эвтектике как при температуре ТЕ, т.е. при равновесной кристаллизации (КРК), так и в области переохлаждения при температуре Тmin на начало неравновесно-взрывной кристаллизации (НРВК).

Эффективность использования аккумуляции холода и холодильной машины

This is continuation of author’s works in energy saving area; the work’s aim is to identify opportunities for energy cost reducing when cold producing by vapor compression chilling machine with variable cooling load. Have been considered schemes, in which the stored cold compensates the cooling load’s peaks. Have been presented the results of thermodynamic calculations, which show the possible ranges of chilling machine performance changing while working together with a cold accumulator. As a device for cold reserve storage have been considered an ice accumulator having short, not exceeding a day “charge-discharge” cycle, and a seasonal cold accumulator charged during the winter.

A STUDY INTO ICE BUILD-UP AND MELTING ON VERTICAL COOLED PIPES

The use of cold accumulators based on the principle of ice build up on the cooled surfaces during off-peak periods and ice melting during on-peak periods is an effective method of electricity bills reduction. Within comparatively short periods of on-peak demand a noticeable amount of thermal energy related to ice melting is to be released, it becomes clear that not only sizing of ice accumulators based on balance calculations is actual, but also the determination of time periods of ice accumulation becomes critical. This work presents experimental unit for obtaining data on the ice build-up on the vertical cooled pipes and later on to continuously register data on the ice thickness diminishing at the regimes of ice melting when cooling of pipe stops. The data for ice build-up and melting for some regimes have been presented and analyzed. The data form the base for deriving semi-empirical correlations allowing to determine a time intervals necessary to generate of ice layers of a given thickness.

Solar Cooling for Mediterranean Region as a Crop Storage Technology

The Mediterranean region is a major supplier of fruits and vegetables to Europe. Fruit harvesting continues the year round, including certain fruits to be harvested from September to June. The follow up of the specific temperature and humidity storage conditions becomes significantly energy intensive that adversely affects the energy balance of exporters, especially when the producing country is run out of affordable energy sources. In order to reduce the energy costs during the crop storage and avoid the crop wastage, the solar ejector cooling systems were introduced. These systems developed recently, are fully autonomous, does not contain mechanically moving parts, reliable and durable in performance. In addition, the new type of thermopump with high energy and performance characteristics was elaborated and tested within the ejector cooling system, driven by the imitated low-grade heat. The results of theoretical and experimental study of the thermopump and the ejector refrigeration system were described in the study along with factors that affect the system's efficiency.The crop storages operating regimes were reviewed during the storage season for the selected products. Temperature ranges defined for systems with constant area ratio ejector at COP values remains stable. Cold accumulators or duplicate conventional systems, applied during the night were considered as backup systems, supporting a non-stop operation.

АГРОЕНЕРГОКОМПЛЕКС МАЙБУТНЬОГО – ДЛЯ ВИРОЩУВАННЯ ТА ПЕРЕРОБКИ ЕКОЛОГІЧНО ЧИСТОЇ ФРУКТОВО-ОВОЧЕВОЇ СИРОВИНИ

The AGROENERGYCOMPLEX (AEC), in which new technology of year-round cultivation and processing of ecologically pure fruit and vegetable raw materials (FVM), is proposed. AEC when implemented in stand-alone greenhouses producing clean (kosher) products – in the changed ground, without the use of mineral fertilizers and synthetic salt mixes hydroponic technology, without watering plants with polluted water, GMO free. AEC grows year – round irrigation of net melt water, lightened be deuterium and sets mode heat - humidity, harvest meets at least 3 times a year.FOS is sorted and the part that has the subsistence for trade counter "not-selling" look "is directly and im-mediately near the site of" lossless aromatics and palatability - dehydrated by freezing. From juices the 40 ÷ 60% liquid concentrates, dry soluble powders and melt water for beverage production are produced, from the husks of FOS-dry insoluble powders. AEC do not consume "from outside" to grow and for processing of FVM or gas, no electricity, no water, no fuel for cars. Uses only internal resources – rain water, as well as the local water, which cleans itself by freeze-out, daily and seasonal temperature difference between the air and the sun's energy. AEC provides for heating and thermal stabilization of greenhouses, work their own power plants and complex on processing FVM heat accumulators phase transition on the roofs of green-houses and underground heat and cold accumulators. Application of new technology of AEC was reviewed at greenhouses squares 10 and 20 ha with harvest of 2548 and 5860 t FVM /year respectively. AEC are especially suitable for areas distant from the cen-tralized electricity and gas supply and is preferred in areas with extremely continental climate.

ДОБОВА ТА СЕЗОННА РІЗНИЦЯ ТЕМПЕРАТУР ДЛЯ ВИРОБНИЦТВА ЕЛЕКТРОЕ-НЕРГІЇ

A new approach is proposed to the use of daily and seasonal air temperature minor difference as well as solar energy for the year-round electricity generation. underground heat and cold accumulators that allow to extend the temperature range for thermal power cycle and self-circulation coolants for heat-supply in the evaporator-condenser heat powered installation are used. The new technology is applicable to power plants with 100 ÷ 1000 kW capacity and is especially suitable for the production of electricity in the rural areas, which are distant from the centralized networks of electricity and gas supply.

Анализ аккумуляции холода

The aim of this article is to identify opportunities of energy saving during the production of cold. Analysis of the cold
 accumulation in refrigeration units with variable refrigeration load was carried out in order to reduce energy consumption.
 Schemes of ice-water and air conditioning installations, which use ice accumulators, are presented. Varieties of ice
 accumulator cycles and calculation results are provided. Reduced cooling efficiency of the two-stage versus single-stage
 cooling is confirmed. The possibility of replacing ice accumulator with seasonal cold accumulator is considered. A onedimensional
 mathematical model of ice buildup in ice accumulator is offered. The calculation results are compared with
 the characteristics of actual products. Energy saving by replacing ice accumulators with seasonal cold accumulators is
 confirmed by the results of calculations.

ПРО ДОІЦІЛЬНІСТЬ ВИКОРИСТАННЯ АКУМУЛЯТОРІВ ХОЛОДУ НА ПІДПРИЄМСТВАХ

The advisability of thermal energy accumulators use in food industry is presented and substantiated in the article. The time graphs of energy consumption for some plants along with the plots of electrical energy payments within a single- triple-zones tariffs as characteristic for the “Danone” diary plant in the city of Kherson have been analyzed. The results obtained have proved that the effectiveness of cold accumulators application is greatly determined not only by the available time of ice accumulation, but also by the achievable speed of the ice melting, which, eventually, determines the amount of ice which is necessary to generate during the accumulator “charge” period. The proposed considerations will be used at the developing of an ice accumulator designe calculations methodology.

РОБОЧІ ТІЛА З ФАЗОВИМ ПЕРЕХОДОМ «РІДИНА-ТВЕРДЕ ТІЛО-РІДИНА» ДЛЯ КРІОХІРУРГІЧНИХ АПАРАТІВ

An autonomous cryosurgical apparatus that uses latent heat of melting of a prefrozen working substance as a source of cold is considered in the present article. The process of the substance freezing is taking place in a cold accumulator that represents a hermetically sealed container. In the course of the phase transitions “liquid - solid body – liquid” amount of the working substance is unchangeable and therefore the cold accumulator can be used repeatedly. A separate refrigerating machine could be used to freeze the working substance in the accumulator and this makes the peculiarity of the apparatus. A Joule-Thomson refrigerating machine of a simple design with a phase separator and operating by use of a zeotropic mixture of refrigerants can advisably be used for this purpose. Thermophysical properties of more than 20 substances candidates with melting temperatures within the range of (-100…-150)°С that is acceptable to the apparatus operating conditions are presented in the article. Ethanol seems to be the most appropriate agent which is in a liquid state under the normal conditions; has the melting/freezing temperature of -114°С and the latent heat of phase transition “solid body – liquid” of 104.4 kJ/kg.

ВИЗНАЧЕННЯ КОЕФІЦІЄНТУ ТЕПЛОВІДДАЧІ ПРИ КИПІННІ ХОЛОДИЛЬНИХ АГЕНТІВ В АКУМУЛЯТОРАХ ХОЛОДУ

The use of correlations that would be capable to adequately account for the heat transfer between the surface and refrigerant are crucial for the accurate design calculations and proper heat transfer equipment sizing, including cold accumulators with ice generation on the heat transfer surface. A vast multitude of such correlations for the determination of overall heat transfer coefficient valid for different cross sections pipes and processes conditions are available now in the literature. The calculations of heat transfer pertinent to the conditions of cold accumulators, lead to the results drastically deviating from those obtained in the framework of the direct experimentation carried out at the Department of Power Engineering and Industrial Refrigeration of NUFT. In order to mark one or some of such correlations, that might have been used within the engineering calculations under condition of their proper correction, the critical comparative analysis of the literature sources has been carried out. The mathematical modeling of the heat transfer process in the condition of boiling refrigerant, with taking into account the valid limitations towards correlations, has been performed. The graphical comparison of the modeling results calculation with chosen correlations is performed. The results of the analysis allowed choosing the correlations, which could be recommended to be used within the engineering design calculations of cold accumulators with the ice accumulation on the heat transfer surface. The applications of such design correlations that adequately reflect the mechanism of heat transfer between the surface and refrigerant would be critical for the accurate design calculations of the transfer equipment of the refrigeration units, including cold accumulators with ice generation.

Seasional cold accumulator with free-cooling in air conditioning systems

Seasional cold accumulator with free-cooling in air conditioning systems

Повышение эффективности производства холода

The paper is dedicated to the use of renewable energy in cold production, particularly to recycling low temperature heat (below 160
 °C) by the absorption chiller (AС). In most, it is a secondary energy resource, which eliminates carbon emissions and thermal pollution.
 The possibility of increasing the efficiency of cold production for different consumers (including air conditioning) is considered. The
 result is achieved by using a seasonal cold accumulator, which is also a renewable source. Structural diagram and description of
 the workflow are proposed. The example of a single-stage water-ammonia AС illustrates the effect of external temperatures on the
 workflow. Results of thermodynamic calculations prove efficiency of combined AС and seasonal cold accumulator.

Application of sorption heat pumps for increasing of new power sources efficiency

Application of sorption heat pumps for increasing of new power sources efficiencyIn the 21st century the way to increase the efficiency of new sources of energy is directly related with extended exploration of renewable energy. This modern tendency ensures the fuel economy needs to be realized with nature protection. The increasing of new power sources efficiency (cogeneration, trigeneration systems, fuel cells, photovoltaic systems) can be performed by application of solid sorption heat pumps, regrigerators, heat and cold accumulators, heat transformers, natural gas and hydrogen storage systems and efficient heat exchangers.

Theoretical research of a silica gel–water adsorption chiller in a micro combined cooling, heating and power (CCHP) system

A novel micro CCHP system, which is based on a two bed silica gel–water adsorption chiller, is constructed in this work. To reveal the chiller characteristic in this system, a transient model of the adsorption chiller is developed. According to the comparison of the simulated results and experimental data, the presented model shows a good performance in predicting the chiller performance, with both stable and variable heat source temperature. With the analysis of simulated results, it is found that the cooling capacity and the coefficient of performance (COP) of the chiller are influenced significantly by the average value and variation rate of electric load, as well as the average value of cooling load. The water tank also shows a great effect on the chiller performance. To get better performance of the chiller, the water tank should be adopted when the electric load is low or its variation rate is positive, and should not be utilized when the electric load is high or its variation rate is negative. A 500 L water tank is recommended in order to get better performance and acceptable start-up time. Furthermore, to get better performance as well as higher security, a cold accumulator should be adopted.

Traitement des surinfections bronchiques: stabilité des antibiotiques dans les diffuseurs portatifs

AbstractTreatment of Bronchial Superinfections: Data Related to Stability of Antibiotics in Portable Pumps. Introduction.Given many data about the stability of antibiotics in portable pump (elastomer) are lacking, this study was designed to make a point about available data and to evaluate the stability of antibiotics when exposed to temperature within 35°C (average temperature measured in real conditions of use). Material and methodsFirst, to collect information about the stability of antibiotics in portable pump and to confront them with the local antibiotics protocols dedicated to the treatment of bronchial superinfection in patients with cystic fibrosis; second, to evaluate the stability of piperacillin associated with tazobactam at 35°C. ResultsWhile measured concentrations in tazobactam did not show significant variation during the study, piperacillin measurements showed a major reduction of concentration (up to 33%), both time and concentration related to. DiscussionSuch information must be pointed out to prescribers and patients to ensure a cold accumulator is placed in the pump can’ying-bag and to limit the duration of infusion to 24h with a single pump. ConclusionThis experimental program will keep on going with the stability study of both ticarcillin and cefsulodin in portable pump.

Investigation of the water cooling process in a cold accumulator

Investigation of the water cooling process in a cold accumulator

Heat transfer in devices with solid cryogens and its mathematical description

Heat and mass transfer in sublimation cold accumulators (SCA) has been investigated: heat and mass transfer in the porous cryogen, in the gap and at the contact with the heat transfer surface, as well as stability of thecooled object temperature. On the bases of the results, methods and programs of numerical calculation of temperature fields in SCA structures with consideration for phase transitions has been developed.