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This paper presents new concepts for improving management of the electrical load power regeneration of an aircraft. A novel electrical system that allows for load regeneration back to the distribution bus is described. This approach offers the benefits of reduced weight, volume, and cost, as well as improved reliability. Also described is an electrical machine control mechanism that creates motor power to run the prime mover (i.e., the main engine to dissipate the regenerated power). Instead of main engine generation, this approach can be applied to an auxiliary power unit (APU) or power and thermal management system (PTMS). Background information regarding the regeneration concept is presented. The concept definition and the various modes of operation of the improved system are analyzed and described in detail. Results from the dynamic simulation of the system model are included.

Recovery of potable water from wastewater is essential to the success of long-duration human missions to the moon and Mars. Honeywell International and a team from the NASA Johnson Space Center (JSC) are developing a wastewater processing subsystem that is based on centrifugal vacuum distillation. The wastewater processor, which is referred to as the cascade distillation subsystem (CDS), uses an efficient multistage thermodynamic process to produce purified water. A CDS unit employing a five-stage distiller engine was designed, built, and delivered to the NASA JSC Advanced Water Recovery Systems Development Facility for performance testing; an initial round of testing was completed in fiscal year 2008 (FY08). Based, in part, on FY08 testing, the system is now in development to support an Exploration Life Support Project distillation comparison test that is expected to begin in 2009.

The power and thermal management system (PTMS) developed by Honeywell for aircraft is an integral approach combining the functions of the auxiliary power unit (APU), emergency power unit (EPU), environmental control system (ECS), and thermal management system (TMS). The next generation PTMS discussed in this paper incorporates the new more electric architecture (MEA) and energy efficient aircraft (EEA) initiatives. Advanced system architectures with increased functionality and further integration capabilities with other systems are included. Special emphasis is given to improvements resulting from interactions with the main engine, main electric power generation, and flight actuation. The major drivers for advancement are highlighted, as well as the potential use of new technologies for turbomachinery, heat exchangers, power electronics, and electric machines. More advanced control and protection algorithms are considered.

In association with NASA Glenn Research Center and Lockheed Martin Space Systems, Honeywell has developed and successfully tested an electric power generation system that uses non-toxic hydrogen and oxygen propellants that are reacted catalytically. The resulting fuel-rich gases drive a turbogenerator. Speed control of this system is challenging due to highly variable electric load profile. Discrete two-position valves were used to control the propellant flow for improved reliability compared to proportional valves. This “bang-bang” speed control method exhibits variation in turbine acceleration and deceleration with load. The control thresholds for the turbine speed are adjusted based on load so as to compensate for increased speed overshoot and undershoot.

Launch vehicles that use electric actuators for thrust vector or flight control require a safe, reliable and lightweight source of electrical power. Honeywell, working with NASA Glenn Research Center and Lockheed Martin Space Systems, has developed and successfully tested a turbine-driven electric power generation system which meets these needs. This Turbine Power Unit (TPU) uses hydrogen and oxygen propellants which react catalytically to drive a shaft-speed turboalternator mounted on foil bearings. A high-reactance permanent-magnet machine (HRPMM) was selected for this application. The power conditioning and control electronics can be located within the TPU housing and the hydrogen fuel can be used to pressurize the bearings and electronics and to regeneratively cool the machine. A brassboard unit incorporating many of these features was successfully tested at output power levels from 0 to 138 kilowatts (kW).

Recent advances in the state of the art of space-borne data processors and signal processors have occurred that present some unprecedented constraints relating to their power needs. Such processors include the class of multiprocessors providing computational capabilities in the billions of floating point operations per second. Processors of this type tend to require use of modern radiation tolerant or radiation hardened integrated circuits requiring very low voltage power supplies that place considerable challenge on power distribution and conversion within those processing payloads. The primary challenges are efficient conversion of power from the spacecraft power bus to these low voltages and distribution of the very high accompanying currents within the payload while maintaining proper voltage regulation (typically +/− 5%). Some integrated circuits require 10 Amps or more at 1Volt, as an example [3], [6].

The Internal Thermal Control System (ITCS) has been developed jointly by Boeing Corporation, Huntsville, Alabama and Honeywell Engines & Systems, Torrance, California to meet the internal thermal control needs for the International Space Station (ISS). The ITCS provides heat removal for the critical life support systems and thermal conditioning for numerous experiment racks. The ITCS will be fitted on a number of modules on the ISS. The first US Element containing the ITCS, Node 1, was launched in December 1998. Since Node 1 does not contain a pump to circulate the fluid it was not filled with ITCS fluid until after the US Laboratory Module was installed. The second US Element module, US Laboratory Module, which contains the pumps and all the major ITCS control hardware, was launched in February 2001. The third US Element containing the ITCS, the US Airlock, was launched in July 2001.

The ISS (International Space Station) ITCS (Internal Thermal Control System) includes two internal coolant loops that utilize an aqueous based coolant for heat transfer. A silver salt biocide had previously been utilized as an additive in the coolant formulation to control the growth and proliferation of microorganisms within the coolant loops. Ground-based and in-flight testing demonstrated that the silver salt was rapidly depleted, and did not act as an effective long-term biocide. Efforts to select an optimal alternate biocide for the ITCS coolant application have been underway and are now in the final stages. An extensive evaluation of biocides was conducted to down-select to several candidates for test trials and was reported on previously.

The International Space Station (ISS) IATCS (Internal Active Thermal Control System) includes two internal coolant loops that use an aqueous based coolant for heat transfer. A silver salt biocide was used initially as an additive in the coolant formulation to control the growth and proliferation of microorganisms in the coolant loops. Ground-based and in-flight testing has demonstrated that the silver salt is rapidly depleted and not effective as a long-term biocide. Efforts are now underway to select an alternate biocide for the IATCS coolant loop with greatly improved performance. An extensive evaluation of biocides was conducted to select several candidates for test trials.

The International Space Station (ISS) internal thermal control system (ITCS) has been developed jointly by the Boeing Corporation, Huntsville, Alabama, and Honeywell Engines & Systems, Torrance, California, to meet ISS internal thermal control needs. The ITCS provides heat removal for the critical life support systems and thermal conditioning for numerous experiment racks. The ITCS will be fitted on a number of modules on the ISS. The first module, the US Laboratory Module, was launched in February 2001 and is now operational on the ISS. The dual loop system is comprised of a low-temperature loop (LTL) and a moderate-temperature loop (MTL). Each loop has a pump package assembly (PPA), a system flow control assembly (SFCA), a three-way mixing valve (TWMV), several rack flow control assemblies (RFCA), cold plates, pressure sensors, temperature sensors, a pump bypass assembly (PBA), and a heat exchanger.