Researchers from the Korea
Institute of Machinery and Materials (KIMM) seem to have broken a barrier for
the temperature at which heat can be used for cooling in heat pump systems.
This is important because it ultimately means that more cooling can be
generated with the same amount of heat compared to before. Excess
low-temperature waste heat from data centers, for instance, is often discarded
since it cannot be used for cooling, that is, until now. Low-temperature waste
heat below around 40°C (104°F) is not hot enough to use for cooling (that seems
a bit counterintuitive, but it is due to heat exchange).
According to Tech Times:
“The Korea Institute of Machinery and Materials (KIMM)
unveiled a chemical adsorption heat pump integrated with a novel
electrochemical compressor — a combination the institute says has no commercial
equivalent. A 10 kW prototype, manufactured by Samjung Tech Co., is undergoing
demonstration testing as of this announcement.”
They explain the 40°C (104°F)
thermodynamic barrier for conventional adsorption cooling systems below:
“The challenge is thermodynamic. Adsorption cooling
systems — a well-established technology for using waste heat to drive
refrigeration instead of electricity — have a practical floor. Conventional
adsorption cooling systems require a heat source above 70°C (158°F) to
function. Below that temperature, the solid adsorbent material in the system
cannot be regenerated effectively: it cannot release the refrigerant it has
captured, so the cooling cycle stalls.”
The system is a combination of two
technologies working together. KIMM developed the adsorption heat pump part,
the module that extracts energy from low-temperature exhaust and converts it
into cooling. Chung-Ang University developed the electrochemical compressor
that drives the system's pressure cycle.
During operation, a solid chemical
adsorbent is cycled through two phases: adsorption and desorption. This part is
similar to any other adsorption cooling system, except that heat at a lower
temperature can be utilized.
“…during adsorption, the material captures refrigerant
vapor from the evaporator, creating a low-pressure zone that pulls the
refrigerant to evaporate and generate cold; during desorption, the same
material is heated by the waste heat source to release the captured refrigerant
at elevated pressure, which then condenses and returns to the evaporator. In
conventional systems, that desorption phase demands high-temperature driving
heat — the adsorbent simply will not release its captured refrigerant at 40°C (104°F)
with standard sorbent-refrigerant pairs. KIMM redesigned the adsorption bed to
achieve stable desorption at that lower temperature, though the specific
sorbent material used in the prototype has not been publicly disclosed.”
“The result: the new system successfully demonstrated
cooling operation using waste heat at 40°C (104°F), approximately 30°C (54°F)
below the threshold at which conventional adsorption cooling systems can
function.”
Conventional adsorption cooling
systems require a heat source above 70°C (158°F)
The other part of the system is
the compressor, and this deviates even further from conventional technology.
The novel design utilizes an electrical potential
across an ion-exchange membrane to move refrigerant molecules without any
mechanical action. It is based on an electrochemical approach pioneered in the
1980s by GE. In conventional refrigeration systems, the compressor's actions
are mechanical, involving a piston, scroll, or rotary element that compresses
refrigerant gas, generating noise, vibration, heat, and wear that requires
lubricating oil and scheduled maintenance.
In the system designed by KIMM, an
ammonia-hydrogen working fluid is chemically reacted to produce ammonium ions
(NH₄⁺) by DC
current at the anode. The ions are then conducted through a perfluorosulfonic
acid (PFSA) membrane. This is the same basic membrane architecture used in
hydrogen fuel cells. The ions move from the low-pressure side to the
high-pressure side. At the cathode, the ions are reduced back to ammonia gas at
elevated pressure. The effect is basic mechanical compression where refrigerant
gas moves from low to high pressure, except that it is accomplished entirely
electrochemically, with no moving parts, lubrication, or frequent maintenance
required.
Electrochemical heat pumps have
some clear advantages over conventional heat pumps, if the technical challenges
can be overcome. According to a paper by DOE scientists:
“Electrochemical heat pumps (EHPs) offer a promising
alternative to vapor compression systems by enabling direct
electrochemical-to-thermal energy conversion, often with environmentally benign
working fluids that exhibit low or zero global warming potential (GWP).”
There are different kinds of
electrochemical heat pump prototypes, including direct and indirect ones with
different working fluid system types and closed-loop and open-loop versions.
New innovations with different materials and components are being explored.
Tech Times noted that the paper concludes that electrochemical heat pumps:
“…can achieve 10% to 30% higher energy efficiency than
conventional vapor compression systems, with cooling coefficients of
performance ranging from 3.5 to 14.3 under standard conditions. The same review
identified the field's main barriers: membrane degradation over time, electrode
fouling, and capital costs that remain higher than mechanical alternatives. It
also noted a documented lack of prolonged closed-loop system testing — a gap
that applies to the KIMM prototype as well.”
One challenge for scale-up of the
KIMM model is that the membrane area of the compressor requires larger
membranes, which they are working on for a scaled-up version.
KIMM emphasizes its world-leading
adsorption-bed performance. According to KIMM’s announcement:
“The research team also redesigned the adsorption bed,
the core component of the heat pump, achieving a specific cooling power (SCP)
of 346.5 W/kg. This is more than twice the performance of comparable
international technologies…”
The electrochemical compressor is
also noiseless and does not produce vibrations, unlike mechanical compressors,
which makes it potentially usable in places like hospitals, schools, and
residential areas.
The 10kW prototype still needs
third-party validation, especially to confirm KIMM’s SCP estimate.
Tech Times:
“Commercial silica gel-water adsorption chillers
typically achieve SCP figures in the range of 100 to 170 W/kg; advanced
composite adsorbent systems in academic research have reported up to
approximately 200 W/kg. KIMM's claimed 346.5 W/kg, if confirmed by independent
testing, would represent roughly two to three times the performance of current
commercial systems. That independent confirmation has not yet occurred — the
figure is taken from KIMM's own press release, and third-party laboratory
validation will be needed before the claim can be treated as an established
benchmark. The team has produced 74 SCI papers and holds 29 registered patents
through the project, indicating substantial prior research output from which
the prototype emerges.”
Greater energy efficiency means
that more of the system can be powered by low-temperature waste heat and less
by grid electricity, reducing energy costs going forward.
Germany's Energy Efficiency Act
requires new data centers to recover 10% of waste heat in 2026, to rise to 15%
in 2027 and 20% in 2028.
KIMM is currently still testing
the prototype, and plans are in the works for a field demonstration as the next
step toward commercialization.
Tech Times emphasized three main
challenges to commercialization: 1) scale-up validation – they
point out that the heat exchanger design must be “re-engineered for higher
mass flow rates; and the adsorption bed's thermal cycling behavior under
continuous commercial operation has not been demonstrated.” 2)
independent performance verification – this refers mainly to
validating the SCP claim. 3) ammonia safety engineering –
while ammonia has no global warming potential, it does have safety risks. It is
toxic at high concentrations and flammable in air, and it could be dangerous in
enclosed data center environments. Leak detection systems, ventilation design,
and safety protocols will be required, which may add a bit to system costs.
References:
Korean
researchers crack waste heat cooling barrier with noiseless compressor. Roger
Satterfield. Tech Times. August 5, 2026. Korean
researchers crack waste heat cooling barrier with noiseless compressor
Waste
Heat Becomes Cooling Energy… KIMM Develops Next-Generation Heat Pump System: Demonstrates
a heating and cooling system powered by low-temperature waste heat as low as
40°C. National Research Council of Science and Technology. Newswise. August 5, 2026.
Waste
Heat Becomes Cooling Energy… KIMM Develops Next-Generation Heat Pump System |
Newswise
A
Critical Review of Electrochemical Heat Pump Technologies: Status, Challenges,
and Perspectives. Mingjie Zhua, Elias N. Pergantisa,b, Junyoung Kimc, Chaoran
Daia, Nelson Jamesd, Jinwoo Ohe, Aravind Babyf, Joaquín Rodríguez-Lópezf,
Eckhard A. Grolla, James E. Brauna, and Davide Ziviania. U.S. Department of
Energy. November 2025. A Critical Review of
Electrochemical Heat Pump Technologies: Status, Challenges, and Perspectives
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