Cooling Unit Research Articles

Spray Cooling Unit for Heat Treatment of Stainless Steel Sheets

Stainless steel sheets are successively heated to a temperature of 1150°C and cooled until ambient temperature during the production process. Requirements for high cooling rates of stainless steel sheets producers lead to use water as a cooling medium. The information about cooling intensity (heat transfer coefficient) of different nozzles configurations is necessary for designing cooling sections. Although many researchers deal with water spray cooling, actually a general correlation for predicting heat transfer coefficient for wide range of nozzles configurations does not exists. That is the reason why heat transfer coefficient for different nozzles configurations can be only obtained by laboratory measurements. Heat transfer coefficient is mostly influenced by water impingement density and impact velocity. However other factors e.g. water temperature and velocity of the sheet can influence the heat transfer coefficient. Optimized design of the cooling unit with high cooling intensity and low water consumption was achieved by appropriate choice of these parameters. The moving experimental sheet was cooled from a temperature of 900°C to a temperature of 50°C with various configurations of nozzles. The tests shown that heat transfer coefficient was increasing with water impingement density and impact velocity. Increasing water temperature from 20 °C to 80 °C caused a decrease of the heat transfer coefficient and Leidenfrost temperature. The effect of velocity is negligible when velocities are between 25 and 100 m/min. The cooling unit was designed according to laboratory measurements to fulfill the stainless steel producer's requirements. The measurements which were done in an industrial plant confirmed the accuracy of heat transfer coefficient obtained in the laboratory. The maximum difference between laboratory and plant measurements was 15%.

Experimental investigation of a portable desalination unit configured by a thermoelectric cooler

Possible use of a novel portable desalination system was investigated experimentally. The system is based on humidification–dehumidification principle and thermoelectric cooling technique. A thermoelectric cooler was integrated into the system to enhance the process of both humidification and dehumidification. A prototype was fabricated and its performance was tested for various working conditions of the prototype to observe complex relation between psychrometric and thermoelectric phenomena. The effect of feed water mass flow rate and air flow velocity on the COP value of the thermoelectric cooler and clean water production of the system were examined. The maximum daily yield of the system and the COP value of the thermoelectric cooler unit were recorded as 143.6g and 0.78, respectively.

Adsorption Study of Silica Gel Particle for Improvement in Design of Adsorption Beds Used in Solar Driven Cooling Units

Simulations using Ansys Fluent 6.3.26 have been performed to look into the adsorption characteristics of a single silica gel particle exposed to saturated humid air streams at Re=108 & 216 and temperature of 300K. The adsorption of the particle has been modeled as a source term in the species and the energy equations using a Linear Driving Force (LDF) equation. The interdependence of the thermal and the water vapor concentration field has been analysed. This work is intended to aid in understanding the adsorption effects in silica gel beds and in their efficient design.

Design of a Dairy Cooling Thermal Storage supported with Secondary Refrigeration Cooling Unit

This manuscript presents the comparison of using the cold water and brine as a storage source of refrigeration for milk cooing process based on the accumulator volume and power consumed at variable of cooling load. Also presents the effective of using cold storage in term of accumulator to reduce the refrigeration capacity and energy saving.This manuscript begins with a derivation of mathematical model represents of cooling system followed with a computer program to integrate and simulate the appropriate equations to evaluate accumulator volume and power required for water and brine system. The results showed that the accumulator volume using cold water was 58 m 3 and 59.21 m 3 for cold brine at the same conditions with 206 kW of maximumcooling load, peak duration of 3.5 hours, water temperature difference 2 C, and operating period of refrigerating unit up to 17 hours a day. Also, it was found the power required to operate the compressor of water system around 45%less than the power needed to operate the compressor of cold brine system.

Research on the Compatibility of the Cooling Unit in an Automotive Exhaust-based Thermoelectric Generator and Engine Cooling System

The temperature difference between the hot and cold sides of thermoelectric modules is a key factor affecting the conversion efficiency of an automotive exhaust-based thermoelectric generator (TEG). In the work discussed in this paper the compatibility of TEG cooling unit and engine cooling system was studied on the basis of the heat transfer characteristics of the TEG. A new engine-cooling system in which a TEG cooling unit was inserted was simulated at high power and high vehicle speed, and at high power and low vehicle speed, to obtain temperatures and flow rates of critical inlets and outlets. The results show that coolant temperature exceeds its boiling point at high power and low vehicle speed, so the new system cannot meet cooling requirements under these conditions. Measures for improvement to optimize the cooling system are proposed, and provide a basis for future research.

Design and performance characteristics of solar adsorption refrigeration system using parabolic trough collector: Experimental and statistical optimization technique

The current work demonstrates a developed model of a solar adsorption refrigeration system with specific requirements and specifications. The recent scheme can be employed as a refrigerator and cooler unit suitable for remote areas. The unit runs through a parabolic trough solar collector (PTC) and uses olive waste as adsorbent with methanol as adsorbate. Cooling production, COP (coefficient of performance, and COPa (cycle gross coefficient of performance) were used to assess the system performance. The system’s design optimum parameters in this study were arrived to through statistical and experimental methods. The lowest temperature attained in the refrigerated space was 4°C and the equivalent ambient temperature was 27°C. The temperature started to decrease steadily at 20:30 – when the actual cooling started – until it reached 4°C at 01:30 in the next day when it rose again. The highest COPa obtained was 0.75.

Containment fan cooler heat transfer calculation during main steam line break for Maanshan PWR plant

A thermal analysis has been performed for the Containment Fan Cooler Unit (FCU) during Main Steam Line Break (MSLB) accident, concurrent with loss of offsite power, for Maanshan PWR plant. The analysis is performed in order to address the waterhammer and two-phase flow issues discussed in USNRC's Generic Letter 96-06 (GL 96-06). Maanshan plant is a twin-unit Westinghouse 3-loop PWR currently operated at rated core thermal power of 2822MWt for each unit. The design basis for containment temperature is Main Steam Line Break (MSLB) accident at power of 2830.5MWt, which results in peak vapor temperature of 387.6°F. The design is such that when MSLB occurs concurrent with loss of offsite power (MSLB/LOOP), both the coolant pump on the secondary side and the fan on the air side of the FCU loose power and coast down. The pump has little inertia and coasts down in 2–3s, while the FCU fan coasts down over much longer period. Before the pump is restored through emergency diesel generator, there is potential for boiling the coolant in the cooling coils by the high-temperature air/steam mixture entering the FCU. The time to boiling depends on the operating pressure of the coolant before the pump is restored. The prediction of the time to boiling is important because it determines whether there is potential for waterhammer or two-phase flow to occur before the pump is restored. If boiling occurs then there exists steam region in the pipe, which may cause the so called condensation induced waterhammer or column closure waterhammer. In either case, a great amount of effort has to be spent to evaluate the waterhammer pressure and even the structural integrity. With respect to this, GOTHIC computer code is used to simulate the thermal response of FCU during MSLB/LOOP. The transient response of containment vapor temperature and vapor saturation temperature presented in FSAR are used as boundary conditions of GOTHIC to drive the heat transfer across the cooling coils given a predetermined condensation heat transfer coefficient and convective heat transfer coefficient. The coolant temperature response has been calculated and compared with the saturation temperature corresponding to the coolant operating pressure to determine the time to boiling. The information is then used as the basis to determine whether the current system design has a sufficient margin to prevent boiling from occurring or whether a betterment engineering and design is required to increase the operating pressure at the coolant pump suction.

Application of the Gmc-1000 and Gmc-2000 Mine Cooling Units for Central Air-Conditioning in Underground Mines / Zastosowanie górniczego urządzenia chłodniczego gmc-1000 i gmc-2000 w centralnej klimatyzacji kopalń podziemnych

The paper describes the design and results of operating measurements of the GMC-1000 and GMC- 2000 Mine Cooling Units. The first part describes the design of the cooling unit and its key components: the chiller, evaporator, condenser, oil cooler, evaporative water cooler and gallery air cooler. The possibilities of use in central air conditioning systems of underground mines are described. The second part discusses the results of the workstation and operating measurements and determines the coefficients for evaluating the performance of the mine cooling unit.

3F2 水の潜熱を利用した空気冷却装置の開発(熱工学1)

3F2 水の潜熱を利用した空気冷却装置の開発(熱工学1)

Grey-box modelling and in situ experimental identification of desiccant rotors

This work focuses on grey-box modelling of desiccant rotors. The main objective is to enhance the accuracy of the desiccant wheel model at off-design conditions, including unbalanced flows and variable rotational speed, by introducing tuneable parameters which can be experimentally identified. In order to perform parameters’ identification on full-scale Desiccant Evaporative Cooling (DEC) units, an ad hoc measurement apparatus has been developed and tested, along with a suitable identification procedure. The core of the measurement apparatus consists of a set of eight sensors which allow measuring the process air temperature profile at the dehumidifier wheel outlet. The apparatus was installed in an experimental DEC setup. With the support of numerical modelling, a methodology to identify the physical parameters of the desiccant wheel has been developed. The method is based on a one-dimensional physical model of the generic rotor channel. The results show that the recorded temperature profiles in a few operating conditions are sufficient to identify the model’s tuneable parameters and that the model’s output is valid over a different and wide range of operating conditions. Moreover, the influence of tuneable parameters on the model predicted temperature profile and the comparison of the experimentally identified parameters with their theoretical expected values are discussed. Finally, it is concluded that the accuracy of the one-dimensional model can be improved when its physical parameters are experimentally identified rather than estimated on the basis of literature data. Therefore, grey-box models of commercial wheels would be very helpful in cases where numerical simulations are employed for the design and control optimization of real life DEC systems.

Locomotive Cooling Systems: A Multi-Domain System Strategy for Efficient and Quieter Cooling Units

An important subsystem in all locomotives is the cooling module with its demand of external energy and the sound emitted. Under specific operational conditions the cooling system is the major noise source and the component with the largest energy consumption. In the work presented the design of mobile cooling systems is revisited in a more integrated manner as compared to the state-of-the-art. The aim is the holistic multi-domain system simulation of the cooling unit and its optimization. For that the complete cooling unit is subdivided in a number of sub-models (water circuit, aerodynamic fan, fan transmission, control unit, etc.) which are interacting with the vehicle and ambient conditions. The complete thermal layout of the cooling system is optimized employing advanced numerical simulation tools. In addition, innovative control strategies are included such as intelligent adaptive control of the forced coolant, anticipated upcoming cooling demand from temperature history, adaptive control strategies for increased efficiency of the fans, etc. The potential reduction of sound power level and energy consumed is evaluated while assessing the cost-benefit ratio. The work is part of the European FP7 transport research project ECOQUEST.

High Quality Cross Sections of Low Melting Point Samples Prepared with Cryo Ion Slicer - Broad Ar Ion Beam Milling Apparatus with a Newly Developed Specimen Cooling Unit

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Simulations and Modelling of Absorption Cooling Unit by Means of Peltier Module

Simulations and Modelling of Absorption Cooling Unit by Means of Peltier Module

Hemodynamic evaluation of arterial and venous cannulae performance in a simulated neonatal extracorporeal life support circuit

To construct an ideal extracorporeal life support (ECLS) circuit in terms of hemodynamic performance, each component of the circuit should be evaluated. Most cannulae manufacturers evaluate their products using water as the priming solution. We conducted this study to evaluate the different sizes of arterial and venous cannulae in a simulated neonatal ECLS circuit primed with human blood. The simulated neonatal ECLS circuit was composed of a Capiox Baby RX05 oxygenator, a Rotaflow centrifugal pump and a heater & cooler unit. Three Medtronic Bio-Medicus arterial cannulae (8Fr, 10Fr, 12Fr) and three venous cannulae (10Fr, 12Fr, 14Fr) were tested in seven combinations (8A-10V, 8A-12V, 10A-10V, 10A-12V, 10A-14V, 12A-12V, 12A-14V). All the experiments were conducted using human blood at a hematocrit of 40% and at a constant temperature of 37°C. The "tip to tip" priming volume of the entire circuit was 135ml. The blood volume of the pseudo patient was 500ml. Flow rates increased linearly with increasing size in both venous and arterial cannulae at the same pump speeds. The increase in flow rate was greater when changing the arterial cannulae (next size larger) compared to changing the venous cannulae (next size larger). The pressure drops of the arterial cannula were correlated with the flow rates, regardless of the pseudo patient pressure and the venous cannula used simultaneously. The results show the difference in flow ranges and pressure drops of seven combinations of arterial and venous cannulae. It also suggests that the arterial cannula, not the venous cannula, has greater impact on the flow rate when a centrifugal pump is used in a neonatal ECLS circuit. The results of this study have been translated to further advancing the clinical practice in our institution.

The post-combustion capture pilot plant Niederaussem–Results of the first half of the testing programme

Abstract As part of the development cooperation of RWE Power, BASF and Linde - aiming at an advanced optimised CO2-scrubbing technology for power plant application - the first post-combustion capture pilot plant in Germany was constructed and commissioned at the lignite-fired 1,000 MW Niederaussem power station in 2009. The pre-assembly of the pilot plant started in October 2008 and commissioning took place in July 2009 as planned. 7.2 t of CO2 per day can be captured from a flue gas slipstream of the power plant downstream of the desulphurisation plant (FGD). The pilot plant comprises optimised components such as a flue gas pre-scrubbing direct contact cooler unit as well as a lean liquid cooler and an interstage cooler that both allow returning the solvent at different absorber heights. During a 6-month campaign, all aspects of the optimised process configuration were tested using 30%-weight MEA as benchmark solvent and the performance of a new advanced amine-based solvent developed by BASF was trialled. This paper summarises the operational experience gained and compares some of the results obtained for MEA with those of the new amine-based solvent.

Impact of Tubing Length on Hemodynamics in a Simulated Neonatal Extracorporeal Life Support Circuit

During extracorporeal life support (ECLS), a large portion of the hemodynamic energy is lost to various components of the circuit. Minimization of this loss in the circuit leads to better vital organ perfusion and decreases the risk of systemic inflammation. In this study, we evaluated the hemodynamic properties of differing lengths of tubing in a simulated neonatal ECLS circuit. The neonatal ECLS circuit used in this study included a Capiox Baby RX05 oxygenator (Terumo Corporation, Tokyo, Japan), a Rotaflow centrifugal pump (MAQUET Cardiopulmonary AG, Hirrlingen, Germany), and a heater and cooler unit. An 8Fr Biomedicus arterial and a 10Fr Biomedicus venous cannula were connected to the pseudopatient. One-fourth inch tubing was used for both the arterial and the venous line. A Hoffman clamp was located upstream from the pseudopatient to maintain a certain patient pressure. Three pressure transducers were placed at different sites: postoxygenator, prearterial cannula, and postarterial cannula. The system was primed with Lactated Ringer's solution; human blood was then added to maintain a hematocrit of 40%. The volume of the pseudopatient was 500mL. We hemodynamically evaluated three circuits with different lengths of tubing: 6, 4, and 2 feet (182.88, 121.92, and 60.96 cm, respectively) for both arterial and venous lines; the priming volumes including all of the components of the circuits were 195, 155, and 115mL, respectively. In each circuit, we measured the pressure drops of the arterial tubing and the arterial cannula, as well as the flow rates at different rpm (1750-3000, 250 intervals) under three patient pressures (40, 60, and 80mm Hg). All the experiments were conducted at 37°C. The pressure drop across the arterial cannula is much larger than that of arterial tubing in all set-ups, especially under high flow rates. Upon cutting the tubing from 6 to 2 feet, the pressure drop of the arterial tubing decreased by half, while the pressure drop of the arterial cannula increased due to the slightly higher flow rates. These results suggest that compared to the arterial tubing, the arterial cannula has a larger impact on the hemodynamics of the circuit. There is a little influence of tubing length on the circuit flow rate.

Small Scale Solar Cooling Unit in Climate Conditions of Latvia: Environmental and Economical Aspects

Small Scale Solar Cooling Unit in Climate Conditions of Latvia: Environmental and Economical Aspects The paper contributes to the analyses from the environmental and economical point of view of small scale solar cooling system in climate conditions of Latvia. Cost analyses show that buildings with a higher cooling load and full load hours have lower costs. For high internal gains, cooling costs are around 1,7 €/kWh and 2,5 €/kWh for buildings with lower internal gains. Despite the fact that solar cooling systems have significant potential to reduce CO2 emissions due to a reduction of electricity consumption, the economic feasibility and attractiveness of solar cooling system is still low.

Optimization model for re-circulating cooling water systems

This paper presents an optimization model for the simultaneous synthesis and detailed design of re-circulating cooling water systems. A cooler network superstructure that embeds all network configurations of practical interest is used as part of the integrated model. Pressure drops in each cooler are treated as optimization variables, and design guidelines and constraints are included in order to provide practical and feasible units. The model is based on a generalized disjunctive programming formulation, which gives rise to a mixed-integer nonlinear programming problem. The objective is to find cooling water systems that minimize the total annual cost. Solution of this mathematical formulation provides the optimal system configuration as well as the optimal operating conditions and design parameters required for each cooler unit in the network and in the cooling tower. Three example problems are presented to show the application of the proposed approach.

저궤도 지구관측위성 주탑재체 냉각유닛 설계와 열해석

본 논문은 항우연에서 개발 중인 위성 탑재카메라 FPA-CU(Focal Plane Assembly Cooling Unit) 의 개념설계 및 열설계에 대한 개략적인 내용을 기술하고 있다. FPA-CU은 국내 기술로 설계/제작되는 최초의 우주용 냉각유닛이다. FPA-CU에는 일반적인 히트파이프와 방열판을 이용한 냉각유닛과는 다르게 TBM(Thermal Buffer Mass)이 부착되어 있으므로 열적거동이 기존의 냉각유닛과 다르며, 설계에 있어 천이열전달 해석이 반드시 필요하다. 본 논문에서는 TBM의 용량산출 및 형상적 영향을 포함한 전체 냉각유닛 설계방법을 제시하고 전체 냉각유닛에 대한 열해석 결과를 기술하고 있다. 열해석 결과 냉각유닛의 요구조건을 잘 만족시킴을 알 수 있었으며, 최상단부 히트파이프가 비정상 작동하는 경우 FPA의 온도가 <TEX>$3{\sim}4^{\circ}C$</TEX> 정도 상승함을 알 수 있었다. 본 연구를 통해 위성용 열제어 유닛 설계에 대한 국내 기술적 자립 가능성을 확인할 수 있었다. Thermal analysis and design of FPA(Focal Plane Assembly)-CU(Cooling Unit) for Earth observation camera is performed. FPA-CU is the first cooling device for a spacecraft which is designed and manufactured by its own technology in Korea. FPA-CU has a special feature, TBM(Thermal Buffer Mass) which is discriminated from typical cooling devices using heat pipes and radiator. TBM can be regarded as a thermal energy reservoir and it shows thermally transient characteristics, which make it difficult to design the size and shape of TBM. In current study, a method to determine the volume and the size of TBM is proposed and validated. The transient thermal analysis for FPA-CU for 5 operational scenarios is performed and validates the final design of FPA-CU (Radiator,TBM, Heat pipe I/F). In case of an abnormal operation of a heat pipe among three radiator heat pipes, the temperature of FPA can be increased <TEX>$3{\sim}4^{\circ}C$</TEX> according to the numerical simulation.

A Disjunctive Programming Model for Simultaneous Synthesis and Detailed Design of Cooling Networks

This paper presents a model that simultaneously considers synthesis and detailed design aspects of cooling networks. The model is based on a generalized disjunctive programming formulation that is transformed into a mixed-integer nonlinear program. The objective function is to minimize the total annual cost, which accounts for the cold utility consumption cost, the capital cost for the coolers and pumps, and the pumping costs. The model uses a stagewise superstructure that allows combinations of cooler arrangements in series or in parallel, as well as bypass, mixing, and splitting of the cold utility. The model also incorporates several constraints to meet some specified design codes. In addition to the optimum cooling network configuration, the solution provides the details on the mechanical design features and thermal−hydraulic variables of each cooler unit. Three example problems are presented to show the application of the proposed model.