Studies of Radiative Cooling Systems for Storing Thermal Energy

1989 ◽  
Vol 111 (3) ◽  
pp. 251-256 ◽  
Author(s):  
S. Ito ◽  
N. Miura
Keyword(s):  
Heat Flux ◽  
Energy Storage ◽  
Air Temperature ◽  
Storage Tank ◽  
Cooling System ◽  
Ambient Air ◽  
Radiative Cooling ◽  
Cooling Systems ◽  
Average Temperature ◽  
Radiative Power

The thermal performance of an uncovered radiator and a radiative cooling system was investigated experimentally and theoretically. The net radiative power of a black painted surface at ambient air temperature was measured by heat flux plates at night in order to use the results for predicting temperatures of the radiator surface and the fluid in the cooling system on the same night. The net radiative power obtained by the measurements was 40–60 W/m2 on clear nights in the summer and 60–80 W/m2 in the fall and winter. The average temperature of the energy storage tank on clear nights became 2–5°C below the ambient temperature. The experimental and analytical results agreed well with each other.

scholarly journals Investigating thermal performance of an ice rink cooling system with an underground thermal storage tank

2017 ◽  
Vol 36 (2) ◽  
pp. 314-334 ◽  
Author(s):  
Hakan Tutumlu ◽  
Recep Yumrutaş ◽  
Murtaza Yildirim
Keyword(s):  
Energy Storage ◽  
Analytical Model ◽  
Thermal Performance ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage Tank ◽  
Cooling System ◽  
Operating Time ◽  
Ambient Air ◽  
Coefficient Of Performance

This study deals with mathematical modeling and energy analysis of an ice rink cooling system with an underground thermal energy storage tank. The cooling system consists of an ice rink, chiller unit, and spherical thermal energy storage tank. An analytical model is developed for finding thermal performance of the cooling system. The model is based on formulations for transient heat transfer problem outside the thermal energy storage tank, for the energy needs of chiller unit, and for the ice rink. The solution of the thermal energy storage tank problem is obtained using a similarity transformation and Duhamel superposition techniques. Analytical expressions for heat gain of the ice rink and energy consumption of the chiller unit are derived as a function of inside design air, ambient air, and thermal energy storage tank temperatures. An interactive computer program in Matlab based on the analytical model is prepared for finding hourly variation of water temperature in the thermal energy storage tank, coefficient of performance of the chiller, suitable storage tank volume depending on ice rink area, and timespan required to attain an annually periodic operating condition. Results indicate that operation time of span 6–7 years will be obtained periodically for the system during 10 years operating time.

scholarly journals A Multilayer Emitter Close to Ideal Solar Reflectance for Efficient Daytime Radiative Cooling

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1203 ◽  
Author(s):  
Yeqing Zhu ◽  
Dong Wang ◽  
Cheng Fang ◽  
Ping He ◽  
Yong-Hong Ye
Keyword(s):  
Air Temperature ◽  
Physical Vapor Deposition ◽  
Ambient Air ◽  
Film Structure ◽  
Radiative Cooling ◽  
Atmospheric Conditions ◽  
Cooling Performance ◽  
Average Temperature ◽  
Ambient Air Temperature ◽  
Solar Reflectance

A passive radiative cooling method has a significant influence on thermal management applications because it can cool without any energy input. This work both experimentally and theoretically demonstrates a multilayer thin film structure with high solar reflectance, which can be applied to passive daytime radiative cooling. The combination of physical vapor deposition and spin-coating prepared the samples, which were also characterized experimentally by spectrometers. On-site measured results show that the emitter can effectively achieve daytime radiative cooling, and the cooling performance can be further improved with the increase of the ambient air temperature. When the emitter is exposed to direct solar radiation (AM1.5) of about 880 W/m2 on a rooftop under dry air conditions, it can achieve an average temperature reduction of about 12.6 °C from the ambient air temperature with nonradiative heat transfer (11 a.m.–1 p.m.). Theoretical simulations reveal that the emitter can still have a certain cooling performance in the presence of significant nonradiative heat exchange and nonideal atmospheric conditions. The influence of ambient air temperature on the cooling performance of the emitter is also theoretically analyzed.

Model Predictive Control of a Pumped Two-Phase Cooling System With Microchannel Heat Exchangers

2018 ◽  
Author(s):  
Oyuna Angatkina ◽  
Andrew Alleyne
Keyword(s):  
Heat Flux ◽  
Model Predictive Control ◽  
Predictive Control ◽  
Heat Exchangers ◽  
Cooling System ◽  
High Heat ◽  
High Heat Flux ◽  
Two Phase ◽  
Cooling Systems ◽  
Two Phase Cooling

Two-phase cooling systems provide a viable technology for high–heat flux rejection in electronic systems. They provide high cooling capacity and uniform surface temperature. However, a major restriction of their application is the critical heat flux condition (CHF). This work presents model predictive control (MPC) design for CHF avoidance in two-phase pump driven cooling systems. The system under study includes multiple microchannel heat exchangers in series. The MPC controller performance is compared to the performance of a baseline PI controller. Simulation results show that while both controllers are able to maintain the two-phase cooling system below CHF, MPC has significant reduction in power consumption compared to the baseline controller.

Numerical study of steady natural convection in a liquefied natural gas cylindrical storage tank equipped with baffles

2019 ◽  
Vol 234 (5) ◽  
pp. 709-721 ◽  
Author(s):  
Mohamed Haddar ◽  
Moez Hammami ◽  
Mounir Baccar
Keyword(s):  
Rayleigh Number ◽  
Natural Gas ◽  
Lateral Surface ◽  
Storage Tank ◽  
Cooling System ◽  
Numerical Study ◽  
Gas Storage ◽  
Liquefied Natural Gas ◽  
Natural Gas Storage ◽  
Average Temperature

In this paper, a study of cooling system for a liquefied natural gas storage tank is conducted. Our objective is to remedy the heat ingress to the liquefied natural gas from the environment using baffles toward limiting temperature elevation in the tank, and then the Boil-off Gas (BOG) formation. A specific code based on the finite volume method is developed to supply a fine knowledge of the hydrodynamic and thermal liquefied natural gas characteristics in the cylindrical tank heated from bottom and lateral surfaces. The effect of the number, position and dimension of baffles, on the flow structure and thermal behavior, has been analyzed. According to our simulation results, the baffles should be placed at the top of tank nearby the lateral wall as the liquefied natural gas dimensionless average temperature can be reduced by 36%. The installation of four rectangular baffles, equally spaced around the perimeter of the tank, gives better homogenization of the temperature field and decreases the average temperature by about 44% in order to limit BOG formation. Finally, two correlations of the Nusselt number are established for the flat rectangular baffle plates and the lateral surface of the cylindrical liquefied natural gas storage tank as a function of the Rayleigh number, as well as the baffle number. Scaling of these correlations with the Rayleigh number gives exponents of 0.25 and 0.18 for lateral surface and baffle, respectively, which are in good agreement with literature.

Desiccant Degradation in Desiccant Cooling Systems: An Experimental Study

1993 ◽  
Vol 115 (4) ◽  
pp. 212-219 ◽  
Author(s):  
A. A. Pesaran
Keyword(s):  
Thermal Cycling ◽  
Silica Gel ◽  
Molecular Sieves ◽  
Cooling System ◽  
Ambient Air ◽  
Activated Alumina ◽  
Humid Air ◽  
Cooling Systems ◽  
Degradation Data ◽  
Capacity Loss

We conducted experiments to quantify the effects of thermal cycling and exposure to contamination on solid desiccant materials that may be used in desiccant cooling systems. The source of contamination was cigarette smoke, which is considered one of the worst pollutants in building cooling applications. We exposed five different solid desiccants to “ambient” and “contaminated” humid air: silica gel, activated alumina, activated carbon, molecular sieves, and lithium chloride. We obtained the moisture capacity of samples as a function of exposure time. Compared to virgin desiccant samples, the capacity loss caused by thermal cycling with humid ambient air was 10 percent to 30 percent for all desiccants. The capacity loss because of combined effect of thermal cycling with “smoke-filled” humid air was between 30 percent to 70 percent. The higher losses occurred after four months of experiment time, which is equivalent to four to eight years of field operation. Using a system model and smoke degradation data on silica gel, we predicted that, for low-temperature regeneration, the loss in performance of a ventilation-cycle desiccant cooling system would be between 10 percent to 35 percent, in about eight years, with higher value under worst conditions.

Computational model for a ground coupled space cooling system with an underground energy storage tank

2005 ◽  
Vol 37 (4) ◽  
pp. 353-360 ◽  
Author(s):  
Recep Yumrutaş ◽  
Mehmet Kanoğlu ◽  
Ali Bolatturk ◽  
Mehmet Şirin Bedir
Keyword(s):  
Energy Storage ◽  
Computational Model ◽  
Storage Tank ◽  
Cooling System ◽  
Space Cooling

scholarly journals Innovative Turbine Intake Air Cooling Systems and Their Rational Designing

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6201
Author(s):  
Andrii Radchenko ◽  
Eugeniy Trushliakov ◽  
Krzysztof Kosowski ◽  
Dariusz Mikielewicz ◽  
Mykola Radchenko
Keyword(s):  
Gas Turbines ◽  
Maximum Rate ◽  
Cooling System ◽  
Ambient Air ◽  
Cooling Capacity ◽  
Climatic Conditions ◽  
Air Cooling ◽  
Thermal Loads ◽  
Cooling Systems ◽  
Air Cooling System

The efficiency of cooling ambient air at the inlet of gas turbines in temperate climatic conditions was analyzed and reserves for its enhancing through deep cooling were revealed. A method of logical analysis of the actual operation efficiency of turbine intake air cooling systems in real varying environment, supplemented by the simplest numerical simulation was used to synthesize new solutions. As a result, a novel trend in engine intake air cooling to 7 or 10 °C in temperate climatic conditions by two-stage cooling in chillers of combined type, providing an annual fuel saving of practically 50%, surpasses its value gained due to traditional air cooling to about 15 °C in absorption lithium-bromide chiller of a simple cycle, and is proposed. On analyzing the actual efficiency of turbine intake air cooling system, the current changes in thermal loads on the system in response to varying ambient air parameters were taken into account and annual fuel reduction was considered to be a primary criterion, as an example. The improved methodology of the engine intake air cooling system designing based on the annual effect due to cooling was developed. It involves determining the optimal value of cooling capacity, providing the minimum system sizes at maximum rate of annual effect increment, and its rational value, providing a close to maximum annual effect without system oversizing at the second maximum rate of annual effect increment within the range beyond the first maximum rate. The rational value of design cooling capacity provides practically the maximum annual fuel saving but with the sizes of cooling systems reduced by 15 to 20% due to the correspondingly reduced design cooling capacity of the systems as compared with their values defined by traditional designing focused to cover current peaked short-term thermal loads. The optimal value of cooling capacity providing the minimum sizes of cooling system is very reasonable for applying the energy saving technologies, for instance, based on the thermal storage with accumulating excessive (not consumed) cooling capacities at lowered current thermal loads to cover the peak loads. The application of developed methodology enables revealing the thermal potential for enhancing the efficiency of any combustion engine (gas turbines and engines, internal combustion engines, etc.).

scholarly journals АНАЛІЗ ЕФЕКТИВНОСТІ ОХОЛОДЖЕННЯ ПОВІТРЯ КОГЕНЕРАЦІЙНОГО ГАЗОПОРШНЕВОГО МОДУЛЯ УСТАНОВКИ АВТОНОМНОГО ЕНЕРГОЗАБЕЗПЕЧЕННЯ

2019 ◽  
pp. 76-80
Author(s):  
Андрій Миколайович Радченко ◽  
Анатолій Анатолійович Зубарєв ◽  
Сергій Георгійович Фордуй ◽  
Володимир Володимирович Бойчук ◽  
Віталій Васильович Цуцман
Keyword(s):  
Air Temperature ◽  
Elevated Temperatures ◽  
Cooling System ◽  
Electric Energy ◽  
Ambient Air ◽  
Hot Water ◽  
Lubricating Oil ◽  
Air Cooling ◽  
Air Conditioner ◽  
Engine Room

The analysis of the efficiency of cooling air of cogeneration gas-piston module of installations for combined production of electric energy, heat, and cold is performed. The installation for energy supply includes two JMS 420 GS-N.LC GE Jenbacher cogeneration gas-piston engines manufactured as cogeneration modules with heat exchangers for removing the heat of exhaust gases, scavenge gas-air mixture, cooling water of engine and lubricating oil. The heat of hot water is transformed by the absorption lithium-bromide chiller AR-D500L2 Century into the cold, which is spent on technological needs and for the operation of the central air conditioner for cooling the incoming air of the engine room, wherefrom it is sucked by the turbocharger of the engine. The temperature of the scavenge gas-air mixture at the entrance to the working cylinders of the engine is maintained by the system of recirculating cooling with the removal of its heat into surroundings by the radiator. Because of significant heat influx from working engines and other equipment, as well as through the enclosures of the engine room from the outside to the air-cooled in the central air conditioner in the engine room, from where it is sucked by a turbocharger, the air temperature at the inlet of the turbocharger is quite high: 25...30 °C. At elevated temperatures of the ambient air at the inlet of the radiator for cooling scavenge gas-air mixture and the air at the turbocharger inlet the fuel economy of engine is falling, which indicates the need for efficient cooling of air. The efficiency of cooling the air of the gas-piston module was estimated by a reduction in the consumption of gaseous fuel and the increase in electric power of the engine. For this purpose, the data of monitoring on the fuel efficiency of the gas-piston engine with the combined influence of the ambient air temperature at the inlet of the radiator and the air at the turbocharger inlet were processed to obtain data on their separate effects and to determine the ways to further improve the air cooling system of the gas-piston module.

scholarly journals ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ ГОЛОВНОГО СУДНОВОГО ДВИГУНА АБСОРБЦІЙНОЮ БРОМИСТОЛІТІЄВОЮ ХОЛОДИЛЬНОЮ МАШИНОЮ В ТРОПІЧНИХ УМОВАХ

2020 ◽  
pp. 18-23
Author(s):  
Роман Миколайович Радченко ◽  
Дмитро Вікторович Коновалов ◽  
Максим Андрійович Пирисунько ◽  
Чжан Цян ◽  
Луо Зевей
Keyword(s):  
Air Temperature ◽  
High Efficiency ◽  
Waste Heat ◽  
Cooling System ◽  
Ambient Air ◽  
Climatic Conditions ◽  
Air Cooling ◽  
Exhaust Gas ◽  
Low Speed ◽  
Speed Engine

The efficiency of air cooling at the inlet of the main low speed engine of a transport vessel during operation in tropical climatic conditions on the Shanghai-Karachi-Shanghai route was analyzed. The peculiarity of the tropical climate is the high relative humidity of the air at the same time its high temperatures, and hence the increased thermal load on the cooling system, which requires efficient transformation of the waste heat into the cold in the case of the use of waste heat recovery refrigeration machines. The cooling of the air at the inlet of the low speed engine by absorption lithium bromide chillers, which are characterized by high efficiency of transformation of waste heat into cold – by high coefficients of performance, is investigated. A schematic-construction solution of the air cooling system at the inlet of the ship's main engine using the heat of exhaust gases by an absorption chiller is proposed and analyzed. With this the cooling potential of the inlet air cooling from the current ambient air temperature to 15 ° C and the corresponding heat consumption for the operation of the adsorption chiller, on the one hand, was compared with the available exhaust gas heat potential, on the other hand. The effect of using the exhaust gas heat to cool the air at the inlet of the engine has been analyzed taking into account the changing climatic conditions during the voyage. Enhancement of fuel efficiency of the ship's engine by reducing the inlet air temperature were evaluated by current values of the reduction in specific and total fuel consumption. It is shown that due to the high efficiency of heat conversion in absorption chillers (high coefficients of performance 0.7…0.8), a significant amount of excessive exhaust gas heat over the heat required to cool the ambient air at the inlet of the engine to 15 ° C, which reaches almost half of the available exhaust gas heat during the Shanghai-Karachi-Shanghai route. This reveals the possibility of additional cooling a scavenge air too with almost double fuel economy due to the cooling of all cycle air of the low speed engine, including the air at the inlet.

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