The WaHa Vaporator® Engine
Humid air carries water and energy. We keep both.
Most systems pull one value out of humid air and discard the other. The WaHa Vaporator® recovers the energy that other systems throw away and uses it to do the work again. One energy input. Two outputs: pure water and inexpensive dry air.
The problem
The old way leaves half the value in the air.
Humid air holds two things worth having: water vapor, and the thermal energy bound up with it. A dehumidifier keeps the dry air and dumps the water. An atmospheric water generator keeps the water and vents the heat. Each one keeps half and pays full price for it.
The cost of either machine is mostly energy, spent driving that heat in one direction and then letting it go. Recover the heat instead of releasing it, and the economics change.
The engine
A closed loop that pays itself back.
At the center of every WaHa Vaporator® is its thermodynamic engine: a sealed, closed-loop heat pump driving a desiccant wheel. The wheel captures water vapor from the air. The heat pump then releases that water, and as the water condenses back to liquid it gives off latent heat. The engine recovers that heat and feeds it straight into the next release. The energy does not leave the loop. It is used, recovered, and used again.
That recovery is the unlock, and it is protected WaHa intellectual property. It is the reason one energy input produces two finished outputs, and the reason the energy cost stays roughly flat as the air gets drier, rather than climbing the way it does when a system has to chill air all the way to its dew point.
Inside the engine
Adsorption is cheap. Desorption is where the money goes.
Capturing water from air with a desiccant is a two-stage cycle, and the two stages are nowhere near equally expensive. Adsorption costs very little: move humid air across an activated desiccant, and water molecules diffuse into the pores on their own. The bill arrives at the second stage. Before the desiccant can be used again, that water has to be driven back out of it, and conventional machines do that the only way they know how, by burning natural gas or running an electric resistance heater and then blowing the released moisture out an exhaust duct. The energy is bought at full price, used once, and thrown away. Nothing is recovered. That one design decision is what caps the efficiency of every silica gel desiccant wheel on the market.
The WaHa Vaporator® puts a heat pump where the burner used to be. The heat pump does two jobs at the same time: its hot side drives the water out of the desiccant, and its cold side catches that same water as it condenses and hands the energy back.
The framework in four states: the empty structure, a single channel through it, water molecules collecting inside, and the fully water-loaded framework.
Follow the air
- The open path, at the top. Humid air is pulled across the desiccant module and leaves as inexpensive dry air. That is the whole process side. There is no burner in this path and no exhaust leaving it.
- The sealed chamber, below. The desiccant module carries its captured water into an insulated, sealed chamber. Inside the desorption side, air recirculates over the heat pump’s condenser, which rejects its heat into that air and drives the water back out of the desiccant as vapor.
- The crossover. A portion of that hot, vapor-laden air moves across to the condensation side. On the way, the outgoing and returning streams pass through an air-to-air heat exchanger, so the sensible heat that would otherwise be lost between the two chambers stays inside the loop and preheats the air going back to the desiccant.
- The recovery. In the condensation chamber, the vapor meets the evaporator, the cold side of the same heat pump. The vapor condenses to liquid, and the latent heat it releases is absorbed by the evaporator and carried by the refrigerant straight back around to the condenser, where it goes to work releasing the next batch of water. The cooled, dried air returns to the desorption chamber to keep the release going.
- The output. The condensed water collects in the basin. That is where the moisture goes. There is no exhaust duct on this machine because, once the humidity has become water, there is nothing left to vent.
Why the compressor barely has to work
The energy it takes to pull water off a MOF is very close to the latent heat of vaporization of water, which is the energy that same water gives back when it condenses. Because those two quantities nearly match, the heat load on the condenser and the heat load on the evaporator nearly match as well, and the compressor only has to supply the small difference between them. Most of the energy moving through the cycle was never purchased at all. It is the same energy going around again.
The architecture is built to protect that advantage. The temperature difference between condenser and evaporator is kept as small as the duty allows, which raises the coefficient of performance and lowers the energy per liter of water removed. The internal air volume is kept deliberately small, so there is less air to heat and cool on every cycle. And because solid desiccants remove far more moisture per volume of air than chilling air below its dew point does, less air has to be moved in the first place, which takes another bite out of fan energy and pressure drop.
What the seal buys
Sealing and insulating the regeneration chambers is not only about keeping heat in. It has three consequences that show up in how the machine is specified and installed.
- Regeneration cost stops depending on the weather. The engine is isolated from outside conditions, so releasing a kilogram of water costs the same whether the machine is drying hot, humid makeup air in a Gulf summer or cold, dry air inside a walk-in cooler. That is why one platform covers the full range from −20°C to 55°C rather than a family of climate-specific models.
- The water stays clean. The condensed water never contacts ambient air or what it carries, which is why it comes out distilled-grade: no PFAS, no microplastics, no heavy metals, ready to use with no treatment.
- There is nothing to vent. No regeneration air stream leaves the machine, so there is no exhaust duct, no penetration through the building envelope, and no exhaust path to design or permit.
The efficiency comes from the engine, not the material
The architecture is not tied to a single desiccant. Any solid desiccant that regenerates at low temperature works in it, and the desiccant is matched to the humidity profile of the site.
That includes ordinary silica gel, the same material sitting in conventional desiccant wheels today. Run silica gel in a WaHa Vaporator® and it still regenerates for far less energy than it does in a conventional machine, because the conventional machine buys that heat from a burner or a resistance element and vents it, while this one moves the heat and then recovers it. The savings come from the engine, not from a novel material.
Advanced sorbents earn their place at the edges of the operating envelope, where they hold capacity in air far too dry for silica gel to work in at all. That is what extends the machine down to single-digit relative humidity. It is not what makes it efficient.
The architecture shown here is protected in depth by WaHa’s patent portfolio. Explore the patents.
Where the engine came from
The first WaHa Vaporator® was two clothes dryers from Best Buy.
Eugene Kapustin and David Kuo needed to prove one thing: that a solid desiccant could be regenerated with a heat pump instead of a burner, at a fraction of the energy. Rather than design a machine to test the idea, they bought two heat pump clothes dryers, took them apart, and rebuilt them around a desiccant.
The choice of donor was not an accident. A conventional dryer makes heat with a gas burner or an electric element, blows it through wet clothes, and pushes the humid air outdoors through a vent. A heat pump dryer, the kind sold as ventless, does the same job on a completely different principle: it moves heat instead of making it, dries at low temperature, condenses the moisture out of the air into a tank, and recovers the heat released by that condensation to use again on the next pass. Nothing is vented, because the water leaves as water.
A heat pump clothes dryer moves heat rather than making it, condenses the moisture into a tank, and reuses the heat of condensation. The WaHa Vaporator® runs the same cycle on air instead of laundry.
Every part of that description is also a description of the WaHa Vaporator®. The mapping is close to one for one:
- The solid desiccant is the wet clothes. It is the thing holding the water that has to come back out.
- The heat pump engine dries at low temperature, which is why regeneration costs so little compared with a burner or a resistance heater.
- The heat comes back through water vapor condensation, recovered as the vapor turns to liquid and returned to the next release.
- The parts are off the shelf. The first prototype was built from appliance components, and production machines are still built from standard refrigeration parts, which is why any HVAC technician can service one.
Where the two designs part company is on the other half of the cycle, and it is the reason this machine can work outside a laundry room. Both use active desorption: the heat coming off the condenser is blown across the wet load, clothes in one case, desiccant in the other. But a dryer condenses passively. Moist air meets a cold coil, water collects in the tank, and the heat that water gives up as it condenses is largely lost. The WaHa Vaporator® condenses actively, inside a sealed chamber, and captures that heat of condensation to drive the next release. A clothes dryer can afford a semi-sealed cabinet because it lives in a laundry room where conditions barely move. A machine rated from −20°C to 55°C cannot. Sealing the loop is what holds performance across that range, keeps the water from ever touching ambient air, and leaves nothing to vent.
That extra step shows up in the bill. Heat pump dryers are the most efficient dryers sold: ENERGY STAR puts the category at roughly 30 percent less energy than a conventional dryer, and the most efficient models are cited as high as 70 percent. The WaHa Vaporator® begins with the same architecture and goes further, regenerating a MOF at low temperature rather than a fabric load and returning the recovered latent heat to desorption, which a dryer does not do. It delivers inexpensive dry air with 70 to 90 percent less energy than silica gel wheel-based dehumidifiers.
The analogy also answers the question people ask most often about the WaHa Vaporator®, usually with some disbelief: where does the moisture actually go, if there is no exhaust? It goes where it goes in a ventless dryer. It leaves as liquid water. Anyone who owns one of these machines already owns the proof that drying without a vent works; WaHa applies the same principle to a building instead of a laundry load, with a MOF wheel doing the water capture and a patented engine recovering the heat.
From that pair of dismantled dryers came the patented thermodynamic engine at the center of every machine WaHa builds. Explore the WaHa patent portfolio.
One input, two outputs
The same engine, run two ways.
Drinking water from air alone
Distilled-grade water with no PFAS, microplastics, or heavy metals, meeting US EPA, UAE.S 149, and GSO 149. Produced wherever there is air and power, with no source water to draw on and no waste brine to dispose of.
Dry air at a fraction of the energy
Dry air down to a low dew point, produced with 70 to 90 percent less energy than conventional desiccant dehumidifiers that rely on silica gel. The same engine, set to keep the air instead of the water.
Energy
Runs on whatever power the site has.
Reaches its rated output on ordinary grid power, with no precondition and no co-located heat source required.
Runs on solar or wind with battery storage, for fully off-grid and low-carbon deployment.
Takes low-grade waste heat where a site has it, and uses it in place of part of the electrical input.
The engine is built to accept energy from any of these. None of them is required, and the rated output does not depend on which one is available.
Operating envelope
Built for the conditions where water is actually scarce.
The WaHa Vaporator® holds its rated output from −20°C to 55°C and down to 7 percent relative humidity, a mixing ratio of 1 gram of water per kilogram of air. These are the hot, cold, and dry conditions where systems that work by chilling air to its dew point lose output or stop. Because the engine does not depend on the air being near saturation, it keeps producing where the need is greatest.
Proven, not promised
Field results, then patents to protect them.
The platform has run across seven pilot deployments with 99.999 percent uptime, in conditions ranging from desert heat to Nordic cold. It is protected by a deep and growing patent portfolio: explore the full portfolio. The chemistry is shared across the field. The engine that recovers the heat is ours. Read the full field record: Proven, Not Promised.
Pure Water. Inexpensive Dry Air. Anywhere.
One engine. Two outputs. Any energy source.