Thermomodulating Heat Pipe
US20250250033A1
Abstract
A thermomodulating heat pipe is provided including a heat pipe envelope having a capillary wick extending substantially continuously the full length of the heat pipe and a void space interior of the capillary wick. The heat pipe envelope has a nominal evaporator section, a nominal condenser section where the nominal condenser section includes an active condenser portion and an inactive condenser portion, and a reservoir section extending from the inactive condenser portion. At a nominal condition, a heat pipe fluid is provided with a liquid phase filling the capillary wick and a vapor phase filling the void space of the nominal evaporator section and the active condenser portion, a non-condensable gas filling the void space of at least the reservoir section and the inactive condenser portion. Depending on thermal conditions, both prograde and retrograde heat transfer are enabled.
Description (excerpt)
CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of U.S. application Ser. No. 17/824,893, entitled “Thermomodulating Heat Pipe,” filed on May 25, 2022, which claims the benefit of and priority to U.S. Provisional Application Ser. No. 63/192,763, entitled “Thermomodulating Heat Pipe,” filed on May 25, 2021, the entireties of which are incorporated by reference herein. RIGHTS OF THE GOVERNMENT The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty. BACKGROUND OF THE INVENTION Field of the Invention. The present invention relates generally to the field of thermal control, and more specifically to the fields of thermomodulating heat pipes capable of providing variable conductance and diode functions for enhanced spacecraft thermal management. DESCRIPTION OF THE RELATED ART Spacecraft require thermal control or regulation to address several issues, including Heat Acquisition, Heat Collection, Heat Transport, Heat Rejection, Heat Provision (storage), Heat Insulation, and thus in context, Heat Regulation. Heat Acquisition, Collection, Transport, and Rejection focus on taking uncontrolled thermal dissipation (generated heat) from its point of generation to the ultimate space sink. Heat Provision provides time-phasing to deal with thermal transients. Heat Insulation keeps environmental heat loads from overwhelming the thermal control system, and lastly, Heat Regulation permits the thermal control system to adjust its thermal connection to the environment to solve issues such as excessive heat loss in cold environments or excessive environmental heat absorption in hot environments. Heat Regulation can be seen as a capability to combine the tasks of Heat Insulation and Heat Rejection as needed throughout the mission. The Heat Regulation task may be characterized by its level of required temperature precision: many payloads are satisfied enough to stay within a 50 C operational band, while some sensitive science instruments require sub-millikelvin precision. Most development efforts heretofore have focused on providing Heat Regulation to very needy payloads requiring high precision and have neglected simpler solutions to simpler, coarser challenges. There are a variety of insufficient existing solutions to the task of Heat Regulation. The first, and default solution, may be said to be a ‘cold biased’ radiator+heaters+batteries+feedback control. ‘Cold biased’ is an awkward way of saying that the design is intended to provide a cool-enough temperature in the hot environment and that heater power with feedback control maintains a satisfactory temperature on the thermal radiator. This is the most common form of Heat Regulation and is applied on most thermal radiators on practically every spacecraft. However, this solution provides no hot-side protection and sometimes requires excessive heater power which is usually the stimulus to consider alternatives. A second solution, Thermal Capacitors, which includes both simple thermal masses (often Beryllium blocks) and phase change materials (PCMs) which use their heat of fusion to provide/store heat over melt/freeze cycles. Thermal Capacitors can be used to provide either hot-side or cold-side protection. These tend to be too heavy for all but small/local applications. Thermal switches are a third solution. Thermal switches carry a penalty of excessive thickness in the thermal stackup as well as tending to be too heavy for widespread application. They also have moving parts which makes them unreliable. Thermal switches are only suited for local, niche applications and have not had much acceptance in recent decades. Louvers are a known, but somewhat uncommon solution that tends to be used on outer solar system probes and some earth orbiting spacecraft of the 1980's. Louvers tend to be heavy and their moving parts make them unreliable. However, they've seen a small recent resurgence due to their ability to adjust the effective emissivity of the thermal radiators, thereby providing Heat Regulation to the entire thermal stackup. Deployable or actuatable blankets may be used to cover thermal radiators during cold environments. Deployable blankets are used fairly commonly to provide insulation while spacecraft and their solar arrays are stowed and there is insufficient electrical power to heat any exposed radiators. Stowed solar arrays typically cover most of a spacecraft's thermal radiators and act as deployable blankets in this sense. Deployable blankets are only useful to provide Heat Regulation as a single on-to-off transition. Actuatable blankets have been proposed that could provide frequent and repeated transitions between ‘on’ and ‘off’ states, however these would come with som
Filing details
- Inventors
- Jonathan Allison
- Assignee
- Government Of The United States As Represented By The Secretary Of The Air …
- Filed
- Apr 21, 2025
- Granted
- Application pending
Bibliographic data and excerpted text sourced from Google Patents (public record) as part of IP TechMatch's current-filings monitor. This filing is not part of the 2019 historical archive. For the authoritative full text, drawings, and legal status, see the source links above or consult USPTO records directly.