Browsing by Author "Pauw, Aswin"
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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 Breadboard Testing of a HiPeR Inflatable Radiator (HiPeR INFRA)(49th International Conference on Environmental Systems, 2019-07-07) de Groot, Tom; Schwieters, Boudewijn; van Benthem, Roel; van Es, Johannes; Pauw, AswinWith 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.Item Thermal Analysis and Verification of CubeSat Designs with ESATAN-TMS(50th International Conference on Environmental Systems, 7/12/2021) te Nijenhuis, Arne; Brouwer, Hugo; Jonsson, Martin; Bloem, Edwin; van Donk, Gerrit; Lamers, Bram; Pauw, Aswin; van Benthem, RoelFor the competitive CubeSat market the importance of thermal analysis is often underestimated, which can lead to temperature critical designs. Clearly, with the trend of increasing power density for CubeSats, thermal design deserves more attention. To anticipate on this trend, a joint effort of ISIS - Innovative Solutions in Space and NLR - Royal Netherlands Aerospace Centre was initiated to prepare a framework for modular thermal analysis of CubeSats designs using ESATAN-TMS. In order to increase the accuracy of the initial model parameters used during the verification process, dedicated tests were conducted on specific thermal properties of CubeSats, in order to both verify and supplement literature values. These tests were primarily focused on thermal properties of PCBs, which play a prominent role in the thermal control of CubeSats. Additionally, conductive interfaces of 2U CubeSat assemblies were tested in a thermal vacuum chamber at NLR, and the results were used in the correlation with thermal models. The correlation approach used a black box optimization method for improved fitting of the CubeSat model parameters. In this process the RMS error of the temperature predictions of the CubeSat model is minimised by automatically adjusting a set of pre-defined correlation parameters, amongst which are contact conductance, the thermal conductivity of PCBs and radiative properties, within a pre-defined correlation interval. The verification process as discussed in this paper is the starting point for the creation of a library of validated submodels in ESATAN-TMS which can be used for thermal designs of CubeSats in the future.