1、Best Practices Entry: Best Practice Info:a71 Committee Approval Date: 2000-04-24a71 Center Point of Contact: KSCa71 Submitted by: Wilson HarkinsSubject: Facility Chilled Water for Thermal Conditioning Unit (TCU) Practice: Use of the Facility Chilled Water (FCW) System to provide the heat exchange me
2、dium for the hypergolic propellant Thermal Conditioning Units (TCU).Programs that Certify Usage: This practice has been used on the Space Shuttle Program and the KSC Hypergolic Propellant Loading System.Center to Contact for Information: KSCImplementation Method: This Lesson Learned is based on Main
3、tainability Technique number OPS-15 from NASA Technical Memorandum 4628, Recommended Techniques for Effective Maintainability.Incorporating this technique eliminates the need and cost of a separate cooling system to be designed, installed and maintained at each propellant storage area. Maintainabili
4、ty and reliability of the TCU is greatly enhanced since the individual cooling systems have been removed in lieu of connections to the existing Facility Chilled Water (FCW) System.While at the launch pad the Space Shuttle Orbital Maneuvering System (OMS) and Reaction Control System (RCS) propellant
5、tanks are filled with hypergolic propellant; Monomethylhydrazine (MMH) and Nitrogen Tetroxide (N2O4). The OMS/RCS is used for altitude and attitude changes required by Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-the Shuttle during orbital flight.
6、 Loading of the tanks takes place about two weeks prior to launch. A temperature requirement is imposed on the propellant for loading to assure proper operation of the Ground Support Equipment (GSE) and to assure proper weight measurement of the loaded propellant. The temperature requirement is met
7、by raising or lowering the propellant temperature as required by flowing through the Thermal Conditioning Unit (TCU). If the propellant temperature is below that required, the facility chilled water is heated in the TCU heater before flowing through the heat exchanger where the propellant is brought
8、 up to the required temperature (see figure 1).refer to D descriptionD If the propellant temperature is above that required, the heater is not operated and the FCW provides the heat sink needed to lower the temperature. Each MMH and N2O4storage area has a TCU. The FCW is piped to the propellant stor
9、age areas through insulated tubing from the launch pad FCW system. Filters are provided in the pad FCW system to prevent contaminants from damaging or clogging downstream components.Using the FCW System to provide the heat exchange medium eliminates the need for a separate conditioning unit at each
10、TCU. The previous TCUs used a Freon conditioning unit for temperature control of the propellant. Eliminating those units eliminates the high operating and maintenance costs and environmental concerns associated with each Freon heat exchanger.Reference:1. KSC Drawing 79K05081 - Hypergol System Schema
11、tic Pad 39A.Impact of Non-Practice: An existing FCW system is tapped into to provide the heat exchange medium used for conditioning the hypergolic propellants to the acceptable limits for loading the Space Shuttle tanks. This Provided by IHSNot for ResaleNo reproduction or networking permitted witho
12、ut license from IHS-,-,-eliminated a Freon conditioning unit that was previously installed at each propellant storage area thereby eliminating the associated operating and maintenance expenses.Related Practices: N/AAdditional Info: Approval Info: a71 Approval Date: 2000-04-24a71 Approval Name: Eric Raynora71 Approval Organization: QSa71 Approval Phone Number: 202-358-4738Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
