Browsing by Author "van Gerner, Henk Jan"
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Item Accumulator testing in multiple on-ground orientations for a small Mechanically Pumped Two-phase Loop (MPTL) for CCD thermal control(50th International Conference on Environmental Systems, 7/12/2021) van Es, Johannes; Pauw, Aswin; Van Vliet, Adry; Meng, Qingliang; Zhen Ming, Zhao; van Gerner, Henk JanNLR designed and developed on request and in co-operation with BISME an Engineering Model of a Mechanically Pumped Two-phase Fluid Loop (MPTL) Thermal Control System for CCD thermal control. The objective is to provide accurate thermal control (�1 �C) and a temperature uniformity of <2 �C for nine CCD cameras. The accumulator is a crucial component of such a two-phase pumped thermal control system which allows for loop density changes, and controls the pressure and thereby temperature of the thermal control system. As the accumulator is a large volume with both vapour and liquid, the accumulator is specially designed with internal wick structures for operation in micro-gravity to assure liquid is located at the accumulator inlet and below the accumulator heaters. The design is made such that operation in multiple on-ground orientations is possible. This is demonstrated by tests. The paper starts with a brief overview of the MPTL project and the MPTL design. Subsequently the MPTL accumulator design and the test set-up are explained and test results in various orientations are presented. The paper concludes with an outlook on future MPTL developments and applications.Item Development and Testing of a Two-Phase Mechanically Pumped Loop for Active Antennae(2023 International Conference on Environmental Systems, 2023-07-16) van Gerner, Henk Jan; Kunst, Romaine; van den Berg, T.H; van Es, Johannes; Tailliez, Anne; Walker, Andy; Ortega, Cristina; Iriarte, Mónica; Roldan, Nuria; Ortega Castañeda, Christian; Castro, CharltonThe satellite telecommunications industry is currently undergoing significant evolutions. Future communication satellites need to accommodate a rapidly growing demand in data transfer, combined with more flexibility. For example, there is a strong need for Very High Throughput Satellites capable of delivering up to Tb/s over wide coverage areas. This is only possible when an active phased array antenna is used. However, cooling of active antennas requires the use of a highly efficient thermal control system because it has many heat sources (from hundreds to several thousands), high local heat fluxes (20 W/cm² at evaporator interface), high overall dissipation (around 10 kW), and isothermal requirements on the amplifier chain. These conditions are very difficult to meet with current thermal control solutions (e.g. heat pipes or loop heat pipes), but require a two-phase mechanically pumped fluid loop (MPL). In a MPL, a pump circulates a fluid which evaporates when it absorbs the waste heat from the active antenna. In the IMPACTA project, a demonstrator for such a MPL is being designed and build. This paper describes the test results for the IMPACTA demonstrator. The demonstrator is able to cool a total heat load of 9.8 kW divided over 10 parallel branches with a better than 2°C spatial temperature uniformity over the heat sources. In an active antenna application, the heat load can be unevenly distributed over the different branches. Tests show that even in the extreme case when half of the branches are turned off and the other half are set to full power, no sign of dry-out or too high temperatures is observed, demonstrating the ability of the MPL to cool imbalanced payloads. The demonstrator was tested in 3 different orientations and the test results are similar for all orientations, indicating that the system is not sensitive to gravity effects.Item Development of a Passive Bypass Valve for one and two Phase Fluid Loops for Space Applications(48th International Conference on Environmental Systems, 2018-07-08) van Benthem, Roel; van Es, Johannes; Kay, Nigel; Rose-Innes, Douglas; Garcia, Vincent; Lapensée, Stéphane; van Gerner, Henk Jan; van Donk, Gerrit; van Vliet, AdryTo cope increasing cooling demands, single-phase and two-phase fluidic cooling loops are being developed by European Satellite primes. Innovative components are currently being developed such as the Passive Bypass Valve (PBV) which autonomously diverts flow from the radiator when thermal dissipation is low, maintaining the equipment within the operating temperature range. The objective of the ESA project was to develop an Engineering Model (EM) of the PBV for single-phase and two-phase Mechanically Pumped fluid Loops (MPL) and Loop Heat Pipes (LHP) up to TRL5. The development has been conducted by the Netherlands Aerospace Centre, Nammo and OHB. A trade-off study was done for conceptual designs of the bypass valve including: (1) Bi metallic actuated, (2) Differential temperature actuated, (3) Wax actuated (4) Thermostatic sensor actuated. Technical and non-technical requirements as well as system aspects were rated as well as breadboard testing was done for the most promising concepts. The valve type 4 was selected for the design and manufacturing of the Engineering Model (EM) Passive Bypass valve. The EM valve is hydraulically actuated via capillary tube by expansion of a liquid Galden HT80 inside a remotely located sensor. The EM valve showed an adjustable range (±9⁰C) and repeatable switching as function of temperature (±10⁰ C) in three orientations tested in the single phase MPL. A small hysteresis of ±1.5⁰C (up or down in temperature) has been observed which could be related to the thermal inertia of the hydraulic liquid. The two-phase LHP test showed that the valve stabilized the sensor (payload) temperature around 33⁰±5⁰C (upper limit of the valve) at a condenser temperature of -20⁰C under varying load cases ranging from 500W down to 20W.The conclusion was that EM valve has been successfully developed and tested to TRL 4-5. Activities are defined to improve its maturity further to TRL 5-6.Item Development of an Innovative Diaphragm Pump and Two-Phase Mechanically Pumped Loop for Active Antennas(51st International Conference on Environmental Systems, 7/10/2022) Castro, Charlton; Ortega, Christian; Picton, Kevin; Iriarte, Monica; Ortega, Cristina; van Gerner, Henk Jan; van den Berg, Ramon; van Es, JohannesThe development of Active Phased Array Antennas (APAAs) is a key enabler to effectively accommodate the growing demand of data transfer in commercial telecommunication satellites. A highly efficient and integrated thermal management system is required so as to reject the waste heat produced by the antenna�s Solid State Power Amplifiers (SSPAs). The development of such a thermal control system presents a number of technical challenges, chief among them being the large number of heat sources involved (typically ranging from 100 to 1000, with varying duty cycles), the need for spatial and temporal isothermal conditions across the set of SSPAs, as well as a low thermal gradient between the SSPAs and the working fluid, high total heat dissipation (10+ kW), high heat flux (20+ W/cm^2 at the evaporator�s interface) and large distances between the radiator and the payload, among others. An international consortium led by AVS is currently developing an ammonia two-phase pumped loop for APAAs within the frame of the IMPACTA project. MPLs (two-phase pumped loops in particular) are remarkably well suited for applications involving large heat loads, transfer of thermal energy over large distances (e.g. distributed payloads), high heat fluxes and payloads with tight temperature stability requirements. In addition, a novel positive displacement pump for spacecraft thermal control is being developed by AVS. The pump features a diaphragm architecture, piezoelectric actuator and passive check valves. A series of performance characterization tests of the EM have been conducted using a two-phase mechanically pumped loop test system in laboratory conditions. It is the purpose of the present paper to provide an overview of the IMPACTA project, current status and goals, as well as a description of the PDPump project, outlining the design and main requirements, as well as the development history and current status.Item Fluid selection for space thermal control systems(44th International Conference on Environmental Systems, 2014-07-13) van Gerner, Henk Jan; Benthem, R. C. van; Es, J. van; Schwaller, D.; Lapensée, S.The selection of a suitable fluid is one of the first and most important steps for the design of a thermal control system. For example, for a heat pipe it is important to use a fluid with a high surface tension and heat of evaporation, and a low viscosity. These characteristics can be combined in a ‘figure of Merit’. This figure of Merit is used to pre-select a number of fluids, after which these fluids are further investigated for material compatibility, safety, radiation hardness etc. This systematic approach results in the selection of the most favourable fluid for each application. In this paper, the fluid selections for heat pumps and pumped loops (both single- and two-phase) are discussed. It is explained for instance why CO2 is used in the thermal control system of AMS02 (which was launched with the space shuttle in May 2011 and subsequently mounted on the International Space Station). Also discussed is the selection of Galden HT80 for ESA’s single-phase Mechanically Pumped Fluid Loop (MPFL) and the selection of isopentane for an ESA Heat Pump application.Item A Heat Pump for Space Applications(45th International Conference on Environmental Systems, 2015-07-12) van Gerner, Henk Jan; Donk, G. van; Pauw, A.; Es, J. van; Lapensée, S.In commercial communication satellites, waste heat (5-10kW) has to be radiated into space by radiators. These radiators determine the size of the spacecraft, and a further increase in radiator size (and therefore spacecraft size) to increase the heat rejection capacity is not practical. A heat pump can be used to raise the radiator temperature above the temperature of the equipment, which results in a higher heat rejecting capacity without increasing the size of the radiators. A heat pump also provides the opportunity to use East/West radiators, which become almost as effective as North/South radiators when the temperature is elevated to 100°C. The heat pump works with the vapour compression cycle and requires a compressor. However, commercially available compressors have a high mass (40 kg for 10kW cooling capacity), cause excessive vibrations, and are intended for much lower temperatures (maximum 65°C) than what is required for the space heat pump application (100°C). Dedicated aerospace compressors have been developed with a lower mass (19 kg) and for higher temperatures, but these compressors have a lower efficiency. For this reason, an electrically-driven, high-speed (200,000 RPM), centrifugal compressor system has been developed in a project funded by the European Space Agency (ESA). This novel 3-stage compressor system has a mass of just 2 kg and a higher efficiency than existing aerospace compressors. The compressor system has been incorporated in a heat pump demonstrator, which uses isopentane (R601a) as refrigerant. Due to the exposure of isopentane to radiation in a space application, other substances will form. However, a literature study shows that the amounts of the formed substances are so small, that no significant influence on the performance of the heat pump is expected. Tests were carried out with the heat pump, and at the target setting (saturation temperature of 45°C at the evaporator, 100°C at the condenser, and a payload heat input of 5 kW), the measured COP is 2.3, which is higher than the original requirement of 2.Item Lightweight Two-Phase Pumped Cooling System with Aluminium Components produced with Additive Manufacturing(49th International Conference on Environmental Systems, 2019-07-07) van Gerner, Henk Jan; de Smit, Marc; van Es, Johannes; Migneau, MaximeThe amount of waste heat that is generated in electronic components in aerospace application is increasing because of higher electrical power demands. As a result, conventional cooling methods are not able to maintain the electronic component below its maximum temperature. For this reason, a two-phase Mechanically Pumped Fluid Loop has been developed for high-power electronic components in a commercial aerospace application. These electronic components generate a waste heat of 1200 W that is divided over several hotspots while the temperature gradient over the component has to be kept to a minimum. The developed cooling system uses R245fa as refrigerant and is made from aluminum components produced with additive manufacturing. The use of this novel production technique results in an unprecedented low system mass (2.5 kg) and small system dimensions. Measurements show that the system has an excellent thermal performance and is able to cool 2400W.Item Testing of high heat flux 3D printed aluminium evaporators(48th International Conference on Environmental Systems, 2018-07-08) van Gerner, Henk Jan; de Smit, Marc; van Helvoort, Darron; van Es, JohannesThe amount of waste heat that is generated in electronic components in aerospace application is increasing because of higher electrical power demands. As a result, conventional cooling methods are not able to maintain the electronic component below its maximum temperature. For this reason, a two-phase Mechanically Pumped Fluid Loop is being developed for high-power electronic components in a commercial aerospace application. These electronic components generate a heat load of 722 W on a 3.8 cm x 3.8 cm surface, resulting in a heat flux of 50 W/cm2. Tests with 8 different evaporator samples were carried out to determine the heat transfer coefficients and pressure drop and to select the optimal evaporator sample that is further developed in the detail design phase of the project. The tests show that the 3D printed aluminium evaporators are able to keep the heat source well below its maximum temperature.Item Transient Modelling of Pumped Two-Phase Cooling Systems: Comparison Between Experiment and Simulation with R134a(47th International Conference on Environmental Systems, 2017-07-16) van Gerner, Henk Jan; Bolder, Robin; van Es, JohannesTwo-phase pumped cooling systems are applied when it is required to maintain a very stable temperature in a system, for example in the AMS02, which was launched with a space shuttle (in May 2011) and subsequently mounted on the International Space Station. However, a two-phase pumped cooling system can show complex transient behavior in response to heat load variations. For example, when the heat load is increased, a large volume of vapor is suddenly created, which results in a liquid flow into the accumulator and an increase in the pressure drop. This will result in variations in the temperature in the system, which are undesired. It is necessary to calculate these temperature variations before an application is being built. For this reason, a software tool for transient two-phase systems has been developed by NLR. This tool numerically solves the one-dimensional time-dependent compressible Navier-Stokes equations, and includes the thermal inertia of all the components. In this paper, the numerical results from the model are compared to experimental results obtained with the NLR two-phase test facility with R134a as refrigerant.Item Valve-less Mechanically Pumped Fluid Loop (MPFL) using East and West Panels of a Large Telecommunication Satellite as Radiator(45th International Conference on Environmental Systems, 2015-07-12) Benthem, Roel C. van; van Gerner, Henk Jan; Es, Johannes van; Vliet, Adry van; Put, Patrick van; Elst, Jacques; Schwaller, DavidFor a decade development of a 3-6kW single phase Mechanically Pumped Fluid Loop (MPFL) for active cooling of large telecommunication platforms such AlphaSat is initiated and supported by ESA up to and laboratory demonstration of a full scale loop and (partial) qualification of the loop components such as a pump, bypass valve, pressure transducers and accumulator. Until recently application of MPFL has been postponed by satellite builders because, the performance of conventional thermal solutions such as heat-pipe-networks could be extended to their limits. MPFL makes a more compact design of the satellite structure possible with the heat dissipating transceivers located on an internal structure instead of the conventional location on the side panels. Another option discussed in this paper for application in large geostationary satellites is to install it as a secondary cooling system without valve on the E/W panels. E/W panels are currently hardly used for cooling because parts of the orbit time they are exposed to solar flux that reduces their efficiency. Since the E/W radiators are not exposed to solar flux at the same time and will not become hotter than about +7oC, the E/W radiators are suitable for heat rejection. By arrangement of the payload loop in two sections in series with the East and West radiator a valve for controlling the flow is not needed. A mathematical model of this valve-less MPFL configuration is constructed to predict the thermal/hydraulic performance and orbital temperature stability. Transient thermal analysis and laboratory tests with a full scale loop showed that -without valve- orbital temperature stability of the payload is in the range of ±5.5oC, under variable load conditions. This can be improved by thermally crosslinking payload sections. A valve-less MPFL is therefore a recommended solution as (secondary) cooling system for large geostationary satellites allowing for more compact structural designs (or a higher power density), efficient use of the East/West radiator panels and improved system reliability.