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    Embedded Pulsating Heat Pipe for Improved Heat Spreading in CFRP Equipment Panels for Satellites
    (2023 International Conference on Environmental Systems, 2023) Es, J. van ; Benthem, R.C. van ; Bloem, E.A. ; Klomp - de Boer, R. ; Vliet, A. van ; Sieber, G.
    To avoid hot spots on satellites for equipment mounted on Carbon Fibre Reinforced Polymer (CFRP) panels, there is an increasing demand for improved heat spreading. A technology investigated in this paper is embedding a Pulsating Heat Pipe inside a CFRP sandwich panel. A PHP is a meandering tube partly filled with Ammonia effectively achieving an enhanced conductive value above 10,000 W/m/K along the length of the tubing. Although the physics behind the operation of a PHP is not yet fully understood, it can be constructed based on experimental experience available at the Netherlands Aerospace Centre. The paper describes the design, performance analysis, and manufacturing process of an Engineering Model (EM) of a 0.8 m2 PHP panel. It concludes with performance tests done in a representative environment, achieving TRL 4 to 5. The EM panel has PAN based HT carbon fibre composite face sheets, a carbon foam layer with an embedded pulsating heat pipe tube supported by an aluminium honeycomb. The test programme included leak testing, proof pressure testing, pressure cycle testing, burn-in testing, performance testing in various orientations, and thermal tests in vacuum. In ambient conditions the PHP performed according to expectations with a heat spreading capability > 300 W/m2. However in vacuum the PHP did not operate at all. This unexpected failure is presented including the root cause investigation. The paper ends with an outlook on further research and potential applications.
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    Development of a miniature heat exchanger for mechanically pumped loop systems for active thermal control of CubeSats
    (51st International Conference on Environmental Systems, 2022) Ganzeboom, T.V. ; Es, J. van ; Formisani, L.
    The relatively high power density of CubeSats results in large amounts of heat generated that needs to be dissipated to prevent overheating of a satellite's components. At present, passive thermal control means are used to resolve CubeSats thermal issues, however, as these satellites evolve, advanced active Thermal Control Systems (TCS) will be required. Especially the novel CubeSat propulsion systems require dedicated TCS for the propulsion unit and the corresponding electronics. A promising type of TCS for CubeSats was determined to be the Mini-Mechanically Pumped fluid Loop (Mini-MPL). One such system has been developed at the Royal Netherlands Aerospace Centre (NLR), which consists of a single phase fluid loop that is used for component cooling. One of the important components of this system is the I/F with the Payload. For this purpose a Miniature Payload Heat Exchanger (MPHX) is developed as commercially available heat exchangers are typically impractical for use in space environments. A custom design for the MPHX is presented in this paper. During the design phase, a tool which is able to evaluate the cooling performance of different MPHX models has been built. Using this tool, the three best designs in terms of cooling performance have been identified: the offset strip fin heat exchanger, and two straight channels configurations with respectively triangular and trapezoidal cross sections. The design thermal resistance of the MPHX is in the order of 0.45 K/W with a liquid pressure drop in the order of 1 mbar. The heat exchangers are produced through additive manufacturing (using the Direct Metal Laser Melting method) which allows for greater flexibility and customization of the designs. The models are tested in a pumped fluid loop at the NLR's Thermal Management Facilities to confirm the results predicted in the design phas
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    Breadboard Testing of a HiPeR Inflatable Radiator (HiPeR INFRA)
    (49th International Conference on Environmental Systems, 2019) Groot, T. de ; Schwieters, B. ; Benthem, R.C. van ; Pauw, A. ; Es, J. van
    With a twenty times higher thermal conductivity per unit mass than aluminium, pyrolytic graphite (PG) offers great potential in the application to spacecraft thermal control systems. Over the last years, Airbus Defence and Space Netherlands (Airbus DS NL) has been developing thermal control applications for this material. The patented High Performance Radiator (HiPeR) uses the PG to efficiently spread the heat from a heat source over a large radiative area. Recently, Airbus DS NL and the Royal Netherlands Aerospace Centre (NLR) have been working on a HiPeR Inflatable Radiator (INFRA) application. This concept consists of a HiPeR radiator and a single phase fluid loop. Flexible tubing enables the radiator to be rolled up to a small stowed volume. Once in orbit, the system pressure is increased, triggering the radiator to unroll and maintain its shape over the mission lifetime. Heat is supplied via the same fluid tube that gives the radiator its shape, making use of a dedicated mini-pump. To validate the functional design, a breadboard model has been made. Deployment and thermal performance have been tested successfully. Based on the measured data, the thermal performance of an INFRA system operating at a 45 °C root temperature in a space environment with a sink temperature of -270 °C would be approximately 300-325 W/m2, corresponding to a radiator efficiency of approximately 60%. This performance is deemed to be competitive, especially considering the mass-to-power (expected <10 kg / kW after a design iteration) and small stowed volume of such a system. Additionally, a small-scale breadboard test of protection measures against micro-meteoroids and orbital debris (MMOD) has yielded promising results. The revised design includes MMOD shielding in the form of bi-stable metal strips with a resulting probability of no penetration of the kapton fluid tubing of 0,9 over a lifetime of 15 years.
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    Preliminary design of a mechanically pumped cooling system for active antennae
    (50th International Conference on Environmental Systems, 2021) Gerner, H.J. van ; Berg, T.H. van den ; Es, J. van ; Tailliez, A. ; Walker, A. ; Ortega, C. ; Centeno, M.I. ; Castro, C.
    The 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 and an active phased array antenna is a powerful enabler to achieve that. However, cooling of active antennas requires the use of a highly efficient thermal control system because it has many heat sources (hundred or more), high local heat fluxes (20W/cm� at evaporator interface), high overall dissipation (around 10 kW), and isothermal requirements on the amplifier chain. These conditions are very difficult to solve 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 EU funded IMPACTA project, a demonstrator for such a MPL is being designed and built. This paper describes the preliminary design for this demonstrator, including the fluid selection and tests on evaporator samples.
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    Development and testing of a two-phase mechanically pumped loop for active antennae
    (2023 International Conference on Environmental Systems, 2023) Gerner, H.J. van ; Kunst, R. ; Berg, T.H. van den ; Es, J. van ; Tailliez, A. ; Walker, A. ; Ortega, C. ; Centeno, M.I. ; Roldan, N. ; Castañeda, C.O. ; Castro, C.
    The 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.