Test loops for two-phase thermal management system components

Two mechanically pumped two-phase test rigs were built at NLR in order to experimentally study critical issues of spacecraft two-phase thermal management systems: - a 5 kW, 31 mm ID, freon loop, focusing on the critical components of the ESA Two-Phase Heat Transport System. - a 30000 W, 4.93 mm ID, ammonia loop, to support the development of the...

Development of a sensor for high-quality two-phase flow

The monitoring of the quality of the two-phase mixture at various locations in the system is a valuable, possibly indispensable, part of the control system needed to properly operate a two-phase heat transport system for large spacecraft. Based on a trade-off of various quality monitoring concepts, NLR started to develop a dedicated quality...

Considerations concerning a thermal joint for a deployable or steerable battery radiator for the Columbus Polar Platform

Different concepts for a moveable thermal joint are described and discussed with respect to the applicability in a dedicated deployable or steerable heat pipe radiator system to handle the waste heat of the NiH batteries of the Polar Platform. Concepts which are identified as possible candidates for near-term deployable radiator development are:...

Sensors for a system to control the liquid flow into an evaporative cold plate of a two-phase heat transport system for large spacecraft

Two-phase flow heat transport systems (thermal busses) for the Columbus Space Platform and the Space Station are expected to incorporate systems to control the liquid flow rates into the evaporative cold plates. Such a control system consists of a sensor that monitors the cold plate (performance), a control algorithm and an actuator i.e. a valve...

Limitations in variable conductance heat pipe performance and control predicted by the current steady-state model developed at NLR

A uniaxial model for the transient performance of gas-loaded variable conductance heat pipes is being developed, partly under contract with the Netherlands Agency for Aerospace Programs NIVR. The model has to be easily implementable in existing spacecraft thermal analyzer computer programs. So far, a steady-state version of the model is...

Uniaxial model for gas-loaded variable conductance heat pipe performance : the effects of vapour flow friction and inertia

Warmteoverdracht door straling in een MHD generatorkanaal

Radiation heat transfer is a non-negligible physical process in an open-cycle magnetohydrodymic generator. It constitutes an important part of the energy conservation law, one of the fundamental equations describing the behaviour of the MHD combustion gas in the generator. Radiation heat transfer is modelled following the generally accepted...

Uniaxial model for a gas loaded variable conductance heat pipe

A new uniaxial model for a gas loaded variable conductance heat pipe (VCHP) is developed. This model takes into account the diffusion at the vapour-gas interface as well as the inertial effects of the moving vapour. Only steady-state conditions are considered. The generally accepted Edwards /Marcus model will be shown to be a first order...

Theory and design of conventional heat pipes for space applications

The scope of this report is: - to give a short description of the possible operation principles and applications of heat pipes - to derive the governing equations for a model of a conventional heat pipe (including the limits to the heat transfer capability) - to describe the theoretical derivation of the formulae for the various thermal...

A theoretical investigation of gas conduction effects on multilayer insulation performance

The thermal performance of multilayer insulation hlankets depends on three (interacting) modes of energy transfer: radiation between the radiation shields, gas conduction in the residual interstitial gas and solid conduction via the contacting interfaces. The contribution of the gas conduction depends on the interstitial gas and its pressure,...

Theoretical investigation of the basic thermal performance of multilayer insulation blankets

The thermal performance of evacuated multilayer insulation blankets depends on three modes of energy transfer: radiation between the radiation shields, gas conduction m the residual interstitial gas and solid conduction via the contacting interfaces. The importance of the contributions of the three heat transfer modes depends on many parameters...