Liminal BoundaryOperations
Solid-state water-vapor compression

The boundary is the machine.

We are building a compressor for air conditioners and heat pumps with no moving parts. Water is the refrigerant. A solid-state module does the compressing, right at the boundary where vapor turns to liquid.

See how it works Work with us
Refrigerant
R-718 · H₂O
Global warming potential
0
Moving parts
0
Drops delivered
001048
RefrigerantWaterSealed loop, zero GWP, nonflammable
CompressionIsothermalNo superheated vapor to reject
CompressorSolid stateNo motor, no moving parts
Rating basisAHRI 210/240Residential AC and heat pumps
Technology

Where it fits in a heat pump

Every air conditioner and heat pump moves heat the same way. A refrigerant evaporates indoors, soaking up heat, and condenses outdoors, giving it off. In between, a motor-driven compressor raises the pressure so the outdoor condensing can happen. Our module condenses water vapor directly at the higher pressure, so it takes the place of the condenser and the compressor goes away. As in today's systems, the refrigerant stays sealed inside the loop, so no water is ever added or used up.

With Liminal · sealed water loop
INDOORS OUTDOORS Evaporator indoor coil HEAT FROM YOUR HOME Compressor motor-driven, moving parts ELECTRICITY No compressor vapor flows straight to the condenser Condenser outdoor coil LIMINAL Liminal condenser sealed loop, no water added solid state, no moving parts ELECTRICITY HEAT TO OUTDOORS EXPANSION VALVE LIQUID WATER RETURNS
Refrigerant
Water
Global warming potential
0
Compressor
None
Loop
Sealed · no water added

How the module works inside is shared with partners under a nondisclosure agreement.

Why it matters

Why water, and why solid state

Efficiency

Compress at constant temperature

A mechanical compressor superheats its vapor and has to reject that extra heat as waste. Capturing vapor by condensing it keeps the process at one temperature.

Refrigerant

Zero GWP, nothing to ignite

Water has no global warming potential and does not burn. Like any refrigerant, it stays sealed inside the system. Nothing is sprayed into the air, and no water is added. The low-GWP refrigerants now required in new U.S. residential systems are mildly flammable.

Scale

Small hardware for a bulky vapor

At 7 °C one gram of water vapor fills about 129 liters, far too much for a small mechanical compressor. Condensing it in place removes that limit.

Modeled performance

Higher ceiling, honest floor

At the AHRI 210/240 rating point (7 °C evaporator, 45 °C heat rejection), our ideal cycle needs 332 J of electricity per gram of water moved. That beats an ideal R-32 compressor.

Our loss budget itemizes every anticipated loss in the device. With those losses counted, a three-stage device reaches a coefficient of performance of 3.9 to 4.2, in line with a real R-32 system. These are model results. Phase I is designed to measure them.

Addressable market

A $525 billion industry

Global HVAC sales were about $525 billion in 2025. We enter through dehumidification, which needs only a single stage, then move into data-center cooling, heat pumps and air conditioning.

19%

of U.S. household electricity goes to air conditioning, about 254 billion kWh in 2020 (EIA).

3×

Cooling already takes about a tenth of the world's electricity. Without efficiency gains, its demand could more than triple by 2050 (IEA).

Roadmap

From model to market

The first market is dehumidification, which needs only one stage. Each step after that adds stages and lift.

  1. Stage 1

    Model

    Complete

    Thermodynamic and transport model with an itemized loss budget, built as a tested code package and reviewed by a university faculty collaborator.

  2. Stage 2

    Phase I proof

    In preparation

    A single-stage prototype that captures water vapor from humid air and delivers it as liquid, with the electricity per gram measured against the thermodynamic minimum.

  3. Stage 3

    Dehumidification

    Next

    More stages and higher lift, toward drying air to 50% relative humidity. Modules for HVAC makers, data-center cooling and builders in hot, humid climates.

  4. Stage 4

    Full cooling lift

    Horizon

    Residential split-system air conditioners and heat pumps, then commercial chillers. The core module is licensed to HVAC manufacturers.

Partners

Who we want to hear from

The concept is modeled and the next step is hardware. These are the people who can help us build it.

Grant makers

Program officers and funders

  • NSF SBIR/STTR Phase I proposal in preparation
  • Clear high-risk question with measurable Phase I success criteria
  • Following DOE programs in building efficiency and cooling
  • Federal registration complete, CAGE code assigned

Ask forProject summary, objectives and Phase I plan

Researchers

Labs and faculty

  • Surface and interfacial science of water
  • Water sorption and phase-change measurement
  • Molecular simulation of water at interfaces
  • Heat-exchanger and HVAC test facilities

Ask forTechnical brief and loss model (under NDA)

Vendors

Fabricators and suppliers

  • Advanced materials and coatings
  • Precision fabrication services
  • Low-loss power electronics
  • Humidity and 0.05 K thermal metrology

Ask forPrototype specification (under NDA)

Company

A small company with a narrow focus

Liminal Boundary Operations was founded in 2025 in Phoenix, Arizona to develop one device: a solid-state compressor that uses water as its refrigerant and has no moving parts. Phoenix is a fitting place to work on cooling.

Tyler Heald, Founder and CEO, built the device's thermodynamic and transport model, the tested code package behind every modeled figure on this page. Before founding the company he spent about 15 years as a financial advisor at Vanguard. He has passed the CFA Program and CFP® certification exams.

On a Phase I award we will add a postdoctoral researcher or engineer, and an advisor from the HVAC industry.

Legal name
Liminal Boundary Operations, LLC
Founded
2025
Location
Phoenix, Arizona
Ownership
Founder-owned small business
Federal
SAM.gov registeredCAGE code assigned
Business model
License the core module to HVAC manufacturersSell dehumidification modules first
Contact

Start a conversation

Email works best. Tell us whether you fund, research or supply, and what you would like to see. We will send the right materials.

tyler@lboperations.com