Air–Hydrogen Heat Exchangers for Advanced Space Launchers

in Journal of Propulsion and Power (2009), 25(6),

This paper deals with air–hydrogen heat exchangers intended to provide in-flight oxygen collection capability to a reusable or semireusable two-stages-to-orbit launcher with an oxygen collection phase in ... [more ▼]

This paper deals with air–hydrogen heat exchangers intended to provide in-flight oxygen collection capability to a reusable or semireusable two-stages-to-orbit launcher with an oxygen collection phase in supersonic cruise at Mach 2.5. It aims to present a theoretical but mainly technological and experimental feasibility study of heat exchangers sufficiently efficient and reliable to suit the extreme requirements of this application. Two precoolers of two different types (shell and tubes, and plate and fins) have been selected and designed with the objective of fulfilling all constraints of the concept in terms of performance, leak tightness, reliability, compactness, etc. This design process has been validated with four subscaled breadboards (two of each type) tested on two test benches (for performance and leak tightness), developed by Belgium and Spain, in on-design and off-design conditions. All these results highlight the suitability of the new technologies given the extreme requirements of the concept. An optimum design for each technology is recommended considering its proper advantages and disadvantages. An innovative precooler technology is presented and tested. [less ▲]

Compact Air Separation Technology For In-Flight Oxygen Collection

in 15th AIAA International Space Planes and Hypersonic Systems and Technologies Conference (2008, April)

In the context of an ESA-funded study on an air separation device intended to provide in-flight Oxygen Collection capability to future launchers, experimental and system level investigations are performed ... [more ▼]

In the context of an ESA-funded study on an air separation device intended to provide in-flight Oxygen Collection capability to future launchers, experimental and system level investigations are performed. The project consortium is run by the Université Libre de Bruxelles and includes the Belgian Defence, Techspace Aero (Safran Group) and Liège university among others. In-flight Oxygen Collection has already been described in previous publications, mainly as a conceptual approach. The improvement potentials have been studied and possible uses of the technology go beyond the concept presented here. That is in the aerospace field and also outside, in a much wider range of applications. Hardware work on compact separation are seldom described. As the setup was nearing completion, design know how improved. The last problems were solved and the setup was made fully operational and subject to testing. The following review summarizes the work with latest information on the technological and experimental aspects. In the vehicles using air separation and collection, the cooling capacity of the fuel, liquid hydrogen, is used during a first air breathing phase of the flight to enrich in oxygen and liquefy a fraction of the incoming air. Compact and light weight heat exchanger, coupled to the separator, perform that task. The main advantages of the concept, applied in our preferred concept to TSTO’s, are a much reduced take off mass, a reduced mass for the liquid rocket engines and a much increased operational flexibility in terms of reachable orbit and launch window. Moreover, unlike scramjet propulsion, separation does not rely on high technology material but on readily available material and hardware used with proper design know how and appropriate expertise. The experimental setup development follows a somewhat different route. Liquid and saturated gaseous air are prepared in special heat exchangers before the separator can be fed, the cold source used being liquid nitrogen. The experimental separator itself is, in reality, a 'section' of a real separator. Disposing of the fluids in this machine deserves special care, since pressure has to be controlled while a liquid seal has to be kept stable in most of the operating conditions. Some workarounds had to be developed for that last problem and different solutions were kept available during the testing. Separating is an aspect, interactively measuring -required to tune to proper performance- is another. The operating fluids, that are supposed to be liquid or gaseous in the simple modeling, are in practice often two phase, which is difficult to asses during test and which can strongly impact flow and concentration measurements. High temperature gradients, low temperatures had to be considered for mechanical, sealing and bearing design, nevertheless, strong uncertainty remained before separation results are presented and demonstrate the concept. Most result went above expectations and much further compactification potentials are present. The know how gathered from testing experience allows to foresee improvement directions, both in the global concept and the detail design of a real unit. Those results will allow to extrapolate the real potentials of the separator design developed by our laboratory to the bigger units required for a real concept. [less ▲]

Propulsion vehicle integration for reusable launcher using in-flight oxygen collection

in Aerospace Science and Technology (2007), 12

The use of in-flight oxygen collection has shown to significantly improve space launcher performance. The conceptual approach followed by Belgian teams working on oxygen collection has been to try to ... [more ▼]

The use of in-flight oxygen collection has shown to significantly improve space launcher performance. The conceptual approach followed by Belgian teams working on oxygen collection has been to try to widening the available design margins in order to reduce the required technological leap and limit the economical risk associated with such a development. The aim of the ESA-funded theoretical and experimental study on an air separation device is to demonstrate the possibility of performing efficient air distillation in a compact rotating column. An integration of the vehicle, propulsion system and separation unit designs is presented. The objective is to optimise the overall vehicle performance while keeping technological difficulty and system complexity at a reasonable level. Reference vehicles are presented within their specific mission profiles with an emphasis on TSTO’s. Different layouts of the internal energy and mass flowsheets have been studied and were compared in order to make best use of the refrigeration capacity of the hydrogen fuel running through the propulsion system during the first phase of the flight. In those flowsheets, the separator is considered as a classical distillation tray column. That analysis provides the requirements in terms of heat exchange capacity, compression ratios and number of so-called transfer units needed in the separator. The system is intentionally kept simple to limit complexity, but the analysis is thorough and accurate, including, for example, the effect of the presence of argon. Results for a supersonic carrier are presented. A compact separation unit has been designed in order to reach those requirements. That includes internals, practical building with estimates of pressure drops, separation performance and flow limitation. Main results are given, sizing of the separator bed is provided for a carrier plane showing that such on-board separator is indeed practical. [less ▲]

Breadboard leakage test bench design and construction

Report (2007)

Analysis of Minimal In-Flight Oxygen Collection Cycle for Two Stage Launchers

in 14th AIAA/AHI International Space Planes and Hypersonic Systems and Technologies Conference (2006, November)

PROPULSION AND VEHICLE INTEGRATION FOR REUSABLE LAUNCHER USING IN-FLIGHT OXYGEN COLLECTION

in EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (EUCASS) (2005, July)

The use of in-flight Oxygen Collection has shown to significantly improve space launcher performance. The conceptual approach followed by the Royal Military Academy of Brussels (RMA) has tried to widen ... [more ▼]

The use of in-flight Oxygen Collection has shown to significantly improve space launcher performance. The conceptual approach followed by the Royal Military Academy of Brussels (RMA) has tried to widen the available design margins in order to reduce the required technological leap and limit the economical risk associated with such a development. The aim of the ESA-funded theoretical and experimental study on an air separation device is to demonstrate the possibility of performing efficient air distillation in a compact rotating column. An integration of the vehicle, propulsion system and separation unit designs is presented aiming to optimise the overall vehicle performance while keeping technological difficulty and system complexity at a reasonable level. Reference vehicles are presented in their specific mission profiles with an emphasis on TSTO’s. Different layouts of the internal energy and mass flowsheets have been studied and were compared in order to make best use of the refrigeration capacity of the hydrogen fuel running though the propulsion system during the first phase of the flight considering the separator as a classical distillation column. This analysis provides the requirements in terms of heat exchange capacity, compression ratios and number of so-called transfer units needed in the separator. Here, the system is intentionally kept simple, to limit complexity, but the analysis is thorough and accurate, including, for example, the effect of the presence of argon. Results for a supersonic carrier are presented. An analysis of the separation unit to reach those requirements has been performed. That includes internals, practical building with estimates of pressure drop, separation performance and flow limitation. The sizing of the separator bed is provided for a carrier plane showing that such on-board separator is indeed practical. [less ▲]

Integration of vehicle, propulsion system and separation unit designs for a launcher using in-flight oxygen collection

in AIAA/CIRA 13th International Space Planes and Hypersonics Systems and Technologies Conference (2005, May)

The use of in-flight Oxygen Collection has shown to significantly improve space launcher performance. The conceptual approach followed by the Royal Military Academy of Brussels (RMA) has tried to widen ... [more ▼]

The use of in-flight Oxygen Collection has shown to significantly improve space launcher performance. The conceptual approach followed by the Royal Military Academy of Brussels (RMA) has tried to widen the available design margins in order to reduce the required technological leap and limit the economical risk associated with such a development. The aim of the ESA-funded theoretical and experimental study on an air separation device is to demonstrate the possibility of performing efficient air distillation in a compact rotating column. An integration of the vehicle, propulsion system and separation unit designs is presented aiming to optimise the overall vehicle performance while keeping technological difficulty and system complexity at a reasonable level. Reference vehicles are presented in their specific mission profiles with an emphasis on TSTO’s. Different layouts of the internal energy and mass flowsheets are compared, in order to make best use of the refrigeration capacity of the hydrogen fuel running though the propulsion system during the first phase of the flight considering the separator as a classical distillation column. This analysis provides the requirements in terms of heat exchange capacity, compression ratios and number of so-called transfer units needed in the separator. Here, the system is intentionally kept simple, to limit complexity, but the analysis is thorough and accurate, including, for example, the effect of the presence of argon. An analysis of the separation unit to reach those requirements is proposed. That includes internals, practical building with estimates of pressure drop, separation performance and flow limitation. Analysis of size reduction of the distillation unit from usual 1-g column to the high-g unit is provided as well as the scale up methodology of laboratory results. First experimental results obtained with our centrifugally enhanced distillation separation system are presented and perspectives for a larger on-board operational unit proposed. [less ▲]

Technology Development for In-Flight Oxygen Collection TSTO's

in European Journal of Mechanical and Environmental Engineering, Vol. 48. N° 2. June 2003 (2003, June)