Browsing by Author "Szigetvari, Zoltan"
Now showing 1 - 4 of 4
- Results Per Page
- Sort Options
Item Analysis of Ammonia Moderate Leakage in Columbus(45th International Conference on Environmental Systems, 2015-07-12) Parodi, Paola; Locantore, Ilaria; Palo, Savino De; Szigetvari, Zoltan; Hinderer, StephanThis paper describes the analysis prepared to define the inputs for a timely detection and response to an ammonia moderate leakage from ISS Thermal Control System (TCS) into the Columbus module TCS water loop. Ammonia leakage is currently classified into three levels, with two extremes: the micro-leak, detectable generally via sample/strip analysis methods, the rupture, with a visible (FDIR reaction) flow of ammonia into the water loop, and the intermediate moderate leakage, visible via telemetry. At the time being, neither a moderate leak Flight Rule (FR) nor a dedicated malfunction procedure is available in Columbus’ books, therefore no guidance is provided to the flight team if a leak of that size develops. The advantage of implementing a moderate leakage response is that it covers the ‘gray zone’ between micro-leak and rupture, thus avoiding every leakage greater than the micro-leak to be treated as rupture, with the risk of over-reacting and stopping the activities inside the module when it is not the case.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 IFHX Isolation FDIR – Development and Implementation(48th International Conference on Environmental Systems, 2018-07-08) Szigetvari, Zoltan; Persson, Jan; Malucchi, GiovanniIn 2015, Close Call investigation due to potential freezing of Columbus Moderate Temperature Interface Heat Exchanger lead to the decision of the NASA VCB, held in Oct. 2015, which approved the pursuit related to the general concept to automatically close the Columbus IFHX WOOVs as part of the NASA APM IFHX Leak Response (Ref. NASA VCB presentation: "ITCS Isolation for IFHX Rupture Response"). This paper is describing the development, verification and integration of the European support to the implementation of such an integrated automatic reaction (FDIR). It has been developed via analytically defined sequence operation of the WOOV MkI and MkII at the Columbus IFHX interfaces to contain ammonia entering the Columbus ITCS water loop and to prevent the spread of ammonia and contamination of the Columbus cabin atmosphere in the event of an Interface Heat Exchanger (IFHX) rupture. The following paper provides an overview of the analytical definition, the performed hardware recertification as well as the integration and implementation of the “new” Columbus IFHX Isolation FDIR into the ISS overall ammonia leak protection scenario.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.