Browsing by Author "Bufano, Gaetana"
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Item COLUMBUS Coolant Fluid Servicer – CCFS – Development and Implementation(46th International Conference on Environmental Systems, 2016-07-10) Szigetvari, Zoltan; Hinderer, Stephan; Bufano, GaetanaThe Columbus water cooling loop is of primary importance for proper thermal conditioning and operation of the module subsystem equipment as well as of the scientific payloads. Special care is taken to hydraulically insert and connect equipment or payloads to the Active Thermal Control System (ATCS) water loop which is free of air/gas to avoid the insertion of non-dissolved gases into the loop. The latter, if it happens, might cause cavitation or even damage to the Water Pump Unit (WPU) bearings. Until recently the Hydrocyclone unit had to be inserted into the Columbus water loop to remove the free air from the coolant water. Operation of this equipment was rather crew time consuming hence, an alternative approach had been requested by the European Space Agency (ESA) to be designed and built. Result of the investigations for alternatives revealed a membrane based degassing concept which has been developed, built and verified to fulfil the degassing as well as the water sampling maintenance activities within the ATCS. The following paper provides an overview of the former Columbus Hydrocyclone as well as the development, test, manufacturing, integration and operation of the “new” membrane based coolant fluid servicer.Item Columbus on orbit test: HCU set-point change(48th International Conference on Environmental Systems, 2018-07-08) Bufano, Gaetana; Ferrero, Andrea; Persson, Jan; Szigetvari, ZoltanThis paper describes the test performed on orbit on Columbus on the Heater Control Unit (HCU), the unit that commands the temperature control of the module external shell. Nominally, the HCU on/off set points are 20°C/23°C, while the cabin set point is 23°C. In 2016, upon temporary cabin set point change (from 23 to 19°C), it was pointed out an increase of power consumption by the HCU-controlled heaters. Based on this observation, Flight Control Team (FCT) required to verify the relationship between HCU set points, cabin air temperature and heater power consumption. Since the latter cannot be exactly predicted analytically (too many variables should be considered, e.g. cabin temperature set point, internal power dissipation, beta angle, ISS attitude variation...), an on orbit test was proposed by Engineering Control board (ECB) to integrate the available data. The on orbit HCU limits have been decreased to 18°C (low) and 21°C (high) from beginning of June 2017 to mid of January 2018. This test allowed collecting data over a significant range of beta angles and provided the necessary information to decide how to proceed with the nominal HCU set points. Available operational products allowed to execute this test and to protect against condensation issue if needed. Prior to the test, it was not known whether after decreasing the HCU limits the cabin temperature set point could be guaranteed for any combination of on-orbit conditions (beta angle) and cabin temperature set points (crew preference), therefore the cabin temperature trend was carefully monitored throughout the whole test in order to restore the previous HCU limits, if needed. The test has been successfully completed and preliminary results confirm a remarkable heater power saving and some cabin temperature issues, while the potential condensation issue during Condensing Heat eXchanger (CHX) dry-out is avoided applying the available operational countermeasures.Item WPA Mk I: On orbit and on ground investigations and refurbishment activities(46th International Conference on Environmental Systems, 2016-07-10) Bufano, Gaetana; Truscelli, Gianni; Itta, Antonietta; Bianchi, Renato; Persson, Jan; Hinderer, StephanThis paper describes the flux of on orbit and on ground investigations that have involved the WPA Mk I, from the issue detection to the identification of the subsystem involved, until the detailed investigation of the causes and the WPA refurbishment and re-acceptance. The WPA Mk I was replaced with the spare unit in July 2013, then downloaded and successfully refurbished. The on orbit investigation demonstrated that the hydraulic section had worked properly and that the issue had occurred on the electric section. The ground investigation was composed of two parts, which could not be performed on orbit since the WPA Mk I was a unique ORU, differently from the Mk II that is composed of different ORUs. The first was a series of tests, programmed in such a way to identify whether it had occurred in the motor or in the electronic box: the result was to localize the failure in the electric box. The second was a set of dedicated electrical tests to track down the location of the issue: the result was to identify the failed board. This complex activity required to accurately plan the sequence and the type of tests in order to be able to unambiguously identify the problem. Since no spare units are available for the time being, a re-acceptance campaign of the downloaded and repaired unit is necessary. The re-acceptance campaign is ongoing and once it will be completed the re-accepted unit will be uploaded if necessary. In the meantime the WPA Mk II is undergoing the qualification campaign and when ready it will be launched to replace the current unit. The issue that has been detected on the Mk I is not expected on the Mk II, because on the latter the electronic box is based on a different, more innovative technology.