scholarly journals Optimization of Cascade Cooling System Based on Lithium Bromide Refrigeration in the Polysilicon Industry

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1681
Author(s):  
Shutong Yang ◽  
Youlei Wang ◽  
Yufei Wang
Keyword(s):  
Annual Cost ◽  
Load Distribution ◽  
Heat Load ◽  
Waste Heat ◽  
Cooling System ◽  
Cooling Water ◽  
Total Annual Cost ◽  
Air Cooling ◽  
Water Cooling ◽  
Cooling Methods

Cascade cooling systems containing different cooling methods (e.g., air cooling, water cooling, refrigerating) are used to satisfy the cooling process of hot streams with large temperature spans. An effective cooling system can significantly save energy and costs. In a cascade cooling system, the heat load distribution between different cooling methods has great impacts on the capital cost and operation cost of the system, but the relative optimization method is not well established. In this work, a cascade cooling system containing waste heat recovery, air cooling, water cooling, absorption refrigeration, and compression refrigeration is proposed. The objective is to find the optimal heat load distribution between different cooling methods with the minimum total annual cost. Aspen Plus and MATLAB were combined to solve the established mathematical optimization model, and the genetic algorithm (GA) in MATLAB was adopted to solve the model. A case study in a polysilicon enterprise was used to illustrate the feasibility and economy of the cascade cooling system. Compared to the base case, which only includes air cooling, water cooling, and compression refrigeration, the cascade cooling system can reduce the total annual cost by USD 931,025·y−1 and save 7,800,820 kWh of electricity per year. It also can recover 3139 kW of low-grade waste heat, and generate and replace a cooling capacity of 2404 kW.

scholarly journals ВИЗНАЧЕННЯ РАЦІОНАЛЬНОГО ТЕПЛОВОГО НАВАНТАЖЕННЯ ГРАДИРЕНЬ ВІДВЕДЕННЯ ТЕПЛОТИ У ПРОЦЕСАХ КОНДИЦІЮВАННЯ ПОВІТРЯ НА ВХОДІ ЕНЕРГОУСТАНОВОК

2018 ◽  
pp. 19-22
Author(s):  
Андрій Миколайович Радченко ◽  
Євген Іванович Трушляков ◽  
Сергій Анатолійович Кантор ◽  
Богдан Сергійович Портной
Keyword(s):  
Gas Turbine ◽  
Heat Load ◽  
Turbine Unit ◽  
Waste Heat ◽  
Cooling System ◽  
Lithium Bromide ◽  
Air Cooling ◽  
Cooling Towers ◽  
Gas Turbine Unit ◽  
Heat Loads

The air conditioning processes (heat-humidity treatment) at the inlet of energy units by heat-energized refrigeration mechanisms with heat removal cooling towers of the cooling system are studied on the example of a gas turbine unit. Two-stage air cooling is considered applying a two-stage combined type heat-energized refrigeration mechanism, which applies the exhaust gas heat of a gas turbine unit and which includes absorption lithium-bromide and refrigerant ejector refrigeration mechanism as steps to convert waste heat into cold. Based on the results of modeling the operation of the cooling complex of a gas turbine unit, data was obtained on current heat loads on heat-energized refrigeration mechanisms and cooling towers in accordance with the climatic conditions of operation with different distribution of project heat loads on the air cooling stages and, accordingly, on the transformation of waste heat into cold. Due to the fact that the heat load on the cooling towers depends on the efficiency of transformation of waste heat into cold (heat coefficients) by absorption lithium-bromide and refrigerant ejector refrigeration mechanisms, a rational distribution of the project heat loads to the absorption and ejector stages of a combined type heat-energized refrigeration mechanisms that provides reduce heat load on cooling towers. It is demonstrated that due to this approach to determining the rational heat load on the cooling towers of the cooling system, which consists of calculation the redistribution of heat load between the  absorption lithium-bromide and refrigerant ejector cooling stages with different efficiency and transformation of waste heat (different heat coefficients) in accordance with current climate conditions, is possible to minimize the number of cooling with a corresponding reduction in capital expenditures on the air conditioning system at the inlet of gas turbine unit

scholarly journals ОЦІНКА ЕФЕКТИВНОСТІ ГЛИБОКОГО ОХОЛОДЖЕННЯ ПОВІТРЯ НА ВХОДІ ГТУ ТЕПЛОВИКОРИСТОВУЮЧИМИ ХОЛОДИЛЬНИМИ МАШИНАМИ

2019 ◽  
pp. 10-14
Author(s):  
Андрій Миколайович Радченко ◽  
Богдан Сергійович Портной ◽  
Сергій Анатолійович Кантор ◽  
Ігор Петрович Єсін
Keyword(s):  
Gas Turbine ◽  
Heat Load ◽  
Turbine Unit ◽  
Waste Heat ◽  
Cooling System ◽  
Mechanical Energy ◽  
Ambient Air ◽  
Air Cooling ◽  
Gas Turbine Unit ◽  
Air Cooling System

Significant fluctuations in the current temperature and relative humidity of the ambient air lead to significant changes in the heat load on the air cooling system at the inlet of the gas turbine unit, which urgently poses the problem of choosing their design heat load, as well as evaluating the efficiency of the air cooling system for a certain period of time. The efficiency of deep air cooling at the inlet of gas turbine units was studied with a change during July 2015–2018 for climatic conditions of operation at the compressor station Krasnopolie, Dnepropetrovsk region (Ukraine). For air cooling, the use of a waste heat recovery chiller, which transforms the heat of exhaust gases of gas turbine units into the cold, has been proposed. The efficiency of air cooling at the inlet of gas turbine units for different temperatures has been analyzed: down to 15 °C – an absorption lithium-bromide chiller, which is used as the first high-temperature stage for pre-cooling of ambient air, and down to 10 °C – a combined absorption-ejector chiller (with using a refrigerant low-temperature air cooler as the second stage of air cooling). The effect of air-cooling was assessed by comparing the increase in the production of mechanical energy as a result of an increase in the power of a gas turbine unit and fuel saved during the month of July for 2015-2018 in accumulating. Deeper air cooling at the inlet of the gas turbine unit to a temperature of 10 °C in a combined absorption-ejector chiller compared to its traditional cooling to 15 °C in an absorption bromine-lithium chiller provides a greater increase in net power and fuel saved. It is shown that due to a slight discrepancy between the results obtained for 2015-2018, a preliminary assessment of the efficiency of air cooling at the inlet of gas turbine plants can be carried out for one year.

High Performance Loop Heat Pipe With Flat Evaporator for Energy-Saving Cooling Systems of Supercomputers

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Zhi Hu Xue ◽  
Wei Qu ◽  
Ming Hui Xie
Keyword(s):  
Heat Load ◽  
High Performance ◽  
Operating Temperature ◽  
Cooling Water ◽  
Working Fluid ◽  
Air Cooling ◽  
Water Cooling ◽  
Test Results ◽  
Central Processing ◽  
Flat Evaporator

Abstract Two high performance loop heat pipes (LHPs) are developed for direct cooling of the chips in supercomputer. The two LHPs using flat evaporator are: one called water-cooling LHP and another one called air-cooling LHP. The working fluid of LHP is ammonia. The water-cooling LHP can work well at a heat load up to 663 W and air-cooling LHP can work well at a heat load up to 513 W. The two LHPs applying to the real computer servers are realized and tested. The server test results with water-cooling LHP have shown that the operating temperature of central processing units (CPUs) can be controlled to about 67 °C to ensure the reliable operating and acceptable level for electronic chips, even at condenser-cooling water temperature of 40 °C with low water flowrate of 0.055 m3/h. The server test results with air-cooling LHP have shown that the operating temperature of CPUs can be controlled to about 51 °C even at condenser-cooling wind temperature of 30 °C with wind flowrate of 41.88 m3/h.

Energy Simulations of Data Centers With Hybrid Liquid/Air Cooling and Waste Heat Re-Use

2016 ◽  
Author(s):  
Seungho Mok ◽  
Yogendra K. Joshi ◽  
Satish Kumar ◽  
Ronald R. Hutchins
Keyword(s):  
Data Center ◽  
Computational Models ◽  
Data Centers ◽  
Waste Heat ◽  
Cooling System ◽  
Cooling Water ◽  
Maximum Load ◽  
Air Cooling ◽  
Direct Expansion ◽  
Hybrid Cooling

This study focuses on developing computational models for hybrid or liquid cooled data centers that may reutilize waste heat. A data center with 17 fully populated racks with IBM LS20 blade servers, which consumes 408 kW at the maximum load, is considered. The hybrid cooling system uses a liquid to remove the heat produced by high power components, while the remaining low power components are cooled by air. The paper presents three hybrid cooling scenarios. For the first two cases, air is cooled by direct expansion (DX) cooling system with air-side economizer. Unlike the cooling air, two different approaches for cooling water are investigated: air-cooled chiller and ground water through liquid-to-liquid heat exchanger. Waste heat re-use for pre-heating building water in co-located facilities is also investigated for the second scenario. In addition to the hybrid cooling models, a fully liquid cooling system is modeled as the third scenario for comparison with hybrid cooling systems. By linking the computational models, power usage effectiveness (PUE) for all scenarios can be calculated for selected geographical locations and data center parameters. The paper also presents detailed analyses of the cooling components considered and comparisons of the PUE results.

scholarly journals Water-Cooled Thermoelectric Generators for Improved Net Output Power: A Review

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8329
Author(s):  
Björn Pfeiffelmann ◽  
Ali Cemal Benim ◽  
Franz Joos
Keyword(s):  
Output Power ◽  
Waste Heat ◽  
Cooling System ◽  
Electrical Energy ◽  
Air Cooling ◽  
Thermoelectric Generators ◽  
Water Cooling ◽  
Active Cooling ◽  
Microchannel Cooling ◽  
Low Efficiency

Thermoelectric generators (TEGs) have the ability to convert waste heat into electrical energy under unfavorable conditions and are becoming increasingly popular in academia, but have not yet achieved a broad commercial success, due to the still comparably low efficiency. To increase the efficiency and economic viability of TEGs, research is performed on the materials on one hand and on the system connection on the other. In the latter case, the net output power of the cooling system plays a key role. At first glance, passive cooling seems preferable to active cooling because it does not affect the net electrical output power. However, as shown in the present review, the active cooling is to be preferred for net output power. The situation is similar in air and water-cooling. Even though air-cooling is easier to set up, the water-cooling should be preferred to achieve higher net output power. It is shown that microchannel cooling has similar hydraulic performance to conventional cooling and inserts increase the net output power of TEG. As the review reveals that active water-cooling should be the method of choice to achieve high net output power, it also shows that a careful optimization is necessary to exploit the potential.

Corrosion Resistance of Industrial Pure Titanium and its Alloys under High Temperature and Different Cooling Methods

2021 ◽  
Vol 891 ◽  
pp. 3-9
Author(s):  
Cang Tian Wang ◽  
Qing Long Meng ◽  
Fang Hao Chen ◽  
Jing Hong Wang ◽  
You Ran Zhi ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Acid Corrosion ◽  
Pure Titanium ◽  
Corrosion Current ◽  
Chemical Equipment ◽  
Air Cooling ◽  
Water Cooling ◽  
Corrosion Condition ◽  
Impedance Technique ◽  
Cooling Methods

Industrial pure titanium (TA2) and Ti-6Al-4V (TC4) have been widely available for chemical equipment. However, the corrosion resistance changes during their post-fire performance. In this research, the electrochemical properties of industrial pure titanium and Ti-6Al-4V after heat treatment and different cooling methods were analyzed by AC impedance technique and dynamic polarization method. The results support two conclusions. Firstly, when the temperature is approximate to the phase transition point, for pure titanium and its alloys, water-cooling can obtain better corrosion resistance than air-cooling. With regard to pure titanium, its best corrosion resistance can be obtained at 800°C under water-cooling. For Ti-6Al-4V, its best corrosion resistance can be obtained when the temperature reached 910 °C under water cooling condition. Secondly, the corrosion current density under acid corrosion condition has risen compared with neutral corrosion condition. These results can provide some experimental data and theoretical basis for post-fire anticorrosion performance of titanium materials, and also support the safety, risk evaluation of titanium equipment.

New Thermal Management Systems for Data Centers

2012 ◽  
Vol 4 (3) ◽  
Author(s):  
Mayumi Ouchi ◽  
Yoshiyuki Abe ◽  
Masato Fukagaya ◽  
Takashi Kitagawa ◽  
Haruhiko Ohta ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Single Phase ◽  
Data Centers ◽  
Cooling System ◽  
Heat Pipes ◽  
Air Cooling ◽  
Liquid Cooling ◽  
Two Phase ◽  
Cooling Jacket ◽  
Cooling Methods

Energy consumption in data centers has seen a drastic increase in recent years. In data centers, server racks are cooled down in an indirect way by air-conditioning systems installed to cool the entire server room. This air cooling method is inefficient as information technology (IT) equipment is insufficiently cooled down, whereas the room is overcooled. The development of countermeasures for heat generated by IT equipment is one of the urgent tasks to be accomplished. We, therefore, proposed new liquid cooling systems in which IT equipment is cooled down directly and exhaust heat is not radiated into the server room. Three cooling methods have been developed simultaneously. Two of them involve direct cooling; a cooling jacket is directly attached to the heat source (or CPU in this case) and a single-phase heat exchanger or a two-phase heat exchanger is used as the cooling jacket. The other method involves indirect cooling; heat generated by CPU is transported to the outside of the chassis through flat heat pipes and the condensation sections of the heat pipes are cooled down by coolant with liquid manifold. Verification tests have been conducted by using commercial server racks to which these cooling methods are applied while investigating five R&D components that constitute our liquid cooling systems: the single-phase heat exchanger, the two-phase heat exchanger, high performance flat heat pipes, nanofluid technology, and the plug-in connector. As a result, a 44–53% reduction in energy consumption of cooling facilities with the single-phase cooling system and a 42–50% reduction with the flat heat pipe cooling system were realized compared with conventional air cooling system.

Relative Cooling With Liquid for Gas Turbines: Part I — A Solution for Exceeding 2000 K at Turbine Inlet

2001 ◽  
Author(s):  
Sandu Constantin ◽  
Dan Brasoveanu
Keyword(s):  
Thermal Efficiency ◽  
Gas Turbines ◽  
Cooling System ◽  
Turbine Blades ◽  
Air Cooling ◽  
Liquid Cooling ◽  
Cooling Systems ◽  
Turbine Inlet ◽  
Cooling Methods ◽  
Current Operating

Abstract The thermal efficiency of gas turbines is critically dependent on the temperature of burnt gases at turbine inlet, the higher this temperature the higher the efficiency. Stochiometric combustion would provide maximum efficiency, but in the absence of an internal cooling system, turbine blades cannot tolerate gas temperatures that exceed 1300 K. Therefore, for this temperature, the thermal efficiency of turbine engine is 40% less than theoretical maximum. Conventional air-cooling techniques of turbine blades allow inlet temperatures of about 1500 K on current operating engines yielding thermal efficiency gains of about 6%. New designs, that incorporate advanced air-cooling methods allows inlet temperatures of 1750–1800 K, with a thermal efficiency gain of about 6% relative to current operating engines. This temperature is near the limit allowed by air-cooling systems. Turbine blades can be cooled with air taken from the compressor or with liquid. Cooling systems with air are easier to design but have a relatively low heat transfer capacity and reduce the efficiency of the engine. Some cooling systems with liquid rely on thermal gradients to promote re-circulation from the tip to the root of turbine blades. In this case, the flow and cooling of liquid are restricted. For best results, cooling systems with liquid should use a pump to re-circulate the coolant. In the past, designers tried to place this pump on the engine stator and therefore were unable to avoid high coolant losses because it is impossible to reliably seal the stator-rotor interface. Therefore it was assumed that cooling systems with liquid could not incorporate pumps. This is an unwarranted assumption as shown studying the system in a moving frame of reference that is linked to the rotor. Here is the crucial fact overlooked by previous designers. The relative motion of engine stator with respect to the rotor is sufficient to motivate a cooling pump. Both the pump and heat exchange system that is required to provide rapid cooling of liquid with cold ambient air, could be located within the rotor. Therefore, the entire cooling system can be encapsulated within the rotor and the sealing problem is circumvented. Compared to recent designs that use advanced air-cooling methods, such a liquid cooling system would increase the thermal efficiency by 8%–11% because the temperatures at turbine inlet can reach stoichiometric levels and most of the heat extracted from turbine during cooling is recuperated. The appreciated high reliability of the system will permit a large applicability in aerospace propulsion.

Performance Assessment of Steam Injection Gas Turbine With Inlet Air Cooling

1997 ◽  
Author(s):  
Carlo M. Bartolini ◽  
Danilo Salvi
Keyword(s):  
Ambient Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Power Plants ◽  
Waste Heat ◽  
Cooling System ◽  
Steam Injection ◽  
Maximum Efficiency ◽  
Air Cooling

The steam generated through the use of waste heat recovered from a steam injection gas turbine generally exceeds the maximum mass of steam which can be injected into steam injection gas turbine. The ratio between the steam and air flowing into the engine is not more than 10–15%, as an increase in the pressure ratio can cause the compressor to stall. Naturally, the surplus steam can be utilized for a variety of alternative applications. During the warmer months, the ambient temperature increases and results in reduced thermal efficiency and electrical capacity. An inlet air cooling system for the compressor on a steam injection gas turbine would increase the rating and efficiency of power plants which use this type of equipment. In order to improve the performance of steam injection gas turbines, the authors investigated the option of cooling the intake air to the compressor by harnessing the thermal energy not used to produce the maximum quantity of steam that can be injected into the engine. This alternative use of waste energy makes it possible to reach maximum efficiency in terms of waste recovery. This study examined absorption refrigeration technology, which is one of the various systems adopted to increase efficiency and power rating. The system itself consists of a steam injection gas turbine and a heat recovery and absorption unit, while a computer model was utilized to evaluate the off design performance of the system. The input data required for the model were the following: an operating point, the turbine and compressor curves, the heat recovery and chiller specifications. The performance of an Allison 501 KH steam injection gas plant was analyzed by taking into consideration representative ambient temperature and humidity ranges, the optimal location of the chiller in light of all the factors involved, and which of three possible air cooling systems was the most economically suitable. In order to verify the technical feasibility of the hypothetical model, an economic study was performed on the costs for upgrading the existing steam injection gas cogeneration unit. The results indicate that the estimated pay back period for the project would be four years. In light of these findings, there are clear technical advantages to using gas turbine cogeneration with absorption air cooling in terms of investment.

scholarly journals Some Considerations for EM Cooling Systems

1997 ◽  
Vol 5 (6) ◽  
pp. 18-21
Author(s):  
Allan Mitchell
Keyword(s):  
Electron Microscope ◽  
Water Temperature ◽  
Cooling System ◽  
Cooling Water ◽  
Chloride Concentration ◽  
Closed Circuit ◽  
Water Cooling ◽  
High Chloride Concentration ◽  
Local Water ◽  
Water Cooling System

For numerous reasons a closed-circuit water cooling system is the preferred option for providing cooling water to the electron microscope. Cooling water is required by the electron microscope to cool the diffusion pumps and to keep the electronics' and coiumn temperature stable.A closed-circuit water cooling system is essential if the local water supply has a high chloride concentration, has floating particles, is acidic, has a water temperature that fluctuates and is uncontrollable. This potentially leads to specimen drift problems in the TEW, and/or has a water temperature that is very cold. This potentially leads to condensation problems or diffusion pumps not functioning properly in the TEM.

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