Thermax Vapor Absorption Chillers

The World’s Most-Efficient Vapor Absorption Chillers

Environmentally Friendly Absorption Chillers

As a global leader in vapor absorption chillers, Thermax offers a wide range of energy-efficient, environmentally friendly absorption cooling systems. The chillers use steam, hot water, gas, exhaust gas and mixed fuels as an energy-source alternative to electricity-driven chillers. Thermax provides many capacity options from 15 to 4,500 tons.

Maximize Sustainability and Efficiency

Thermax manufactures the world’s most-efficient absorption chiller. Its technologies integrate well with efficient energy setups such as cogeneration and combined heating, cooling and power (CHPC) systems. Thermax chillers don’t use harmful refrigerants, like CFCs, and are the eco-friendly choice for engineers, contractors and building owners seeking to increase building efficiency.

Highest Coefficient of Performance

Thermax vapor absorption cooling systems offer many benefits, including:

  • Highest-possible Coefficient of Performance (COP)
  • Online concentration measurement
  • Stainless-steel tubes for generator
  • Stainless-steel, plate-type solution heat exchangers
  • Advanced series flow technology
  • Advanced anti-crystallization technology
  • VFD for solution pump
  • PLC-based control panel
  • BMS connectivity
  • Color touchscreen operator interface

Basics of Absorption Cooling

Vapour absorption chillers use water as the refrigerant and a Lithium Bromide (LiBr) solution as the absorbent. The process of cooling goes through stages, including:

  • Evaporation of the refrigerant
  • Absorption of the refrigerant by the concentrated LiBr solution in the absorber
  • Boiling of the diluted LiBr solution to generate refrigerant vapor in the generator
  • Condensation of refrigerant vapor in the condenser

The boiling point of water is directly proportional to pressure. At 6 mm Hg absolute pressure, the boiling point of water is 3.7°C. To change water from liquid to vapor, it has to be heated. The heat, required to change the phase of a liquid to vapor, is called the latent heat of evaporation. 

LiBr is a chemical similar to common salt (NaCl), and is soluble in water. The LiBr water solution has a property to absorb water due to its chemical affinity. As the concentration of LiBr solution increases, its affinity towards water vapor increases. Also, as the temperature of the LiBr solution decreases, its affinity towards water vapor increases. Further, there is a large difference between vapor pressure of LiBr and water. This means that if the LiBr water solution is heated, the water will vaporize but the LiBr will stay in the solution and become concentrated.

The Four Steps of Absorption Cooling


Thermax Single-Effect Steam Absorber

  • Single-effect steam absorption chillers utilize low grade steam from 1.4 – 71 psi to produce chilled water
  • Capacity range: 50 – 2180 TR
  • Efficiency range: 0.7 – 0.8 COP

Thermax Double-Effect Steam Absorber

  • Double-effect steam absorption chillers utilize higher-grade steam ranging from 90-150 psi to produce chilled water at a higher efficiency than single-stage machines. The Thermax design utilizes a series flow configurations in lieu of the less-expensive parallel flow design. This is essential to ensure crystallization doesn’t occur.
  • Capacity range: 120 – 2500 TR
  • Efficiency range: 1.3 – 1.4 COP

Thermax Triple-Effect Steam Absorber

  • Thermax is the first absorption chiller manufacturer in the world to commercialize the ultimate in absorption technology, the Triple-Effect Absorption Chiller. This is a major breakthrough in the field of refrigeration and air conditioning. Triple-effect absorption chillers have a COP of 1.8, which is nearly 30% higher than the double-effect absorption chillers.
  • Cooling capacity: 100 – 1000 TR
  • Steam pressure: 175 – 360 psi
  • Hot water: 375°F – 440°F

Thermax Hot-Water Absorption Chiller

  • Hot-water absorption chillers operate on the same principles as their steam counterparts. The primary difference is that a hot fluid, typically water, is used as the heat source to drive the absorption cycle.
  • Low temperature
    • Low-temperature inlet water temperature: 167°F – 250°F
    • Low-temperature capacities: 10 – 1350 TR
    • Low-temperature COP: 0.65 – 0.8
  •  Medium temperature
    • Medium-temperature inlet water temp: 250° F – 300° F
    • Medium-temperature capacities: 50 – 2000 TR
    • Medium-temperature COP: 0.7 – 0.8
  • High temperature
    • High-temperature inlet water temperature: 300° F – 360° F
    • High-temperature capacities: 50 – 2500 TR
    • High-temperature COP: 1.4 – 1.45

Thermax Specialty-Absorption Chiller

  • Exhaust-driven
  • Exhaust-driven absorption chillers capture heat from exhaust gases, typically from a generator or other gas engine, in order to drive the absorption cycle

Thermax Chiller Heater

  • Provides simultaneous chilled water and hot water
  • 40% energy savings
  • For every 100 kW of cooling, 75 kW of heating can be generated
  • Maximum heating capacity in simultaneous cooling and heating mode: 75-80% of the cooling load
  • In the absence of cooling loads, 100% heating capacity can be produced after changeover to heating mode

Thermax Multi-Energy Absorption Chiller

  • Multi-energy absorption chillers use multiple (typically up to 3) sources of energy to generate cooling. A typical application would be to pair a multi-energy chiller to a gas engine so that the excess heat can be captured through the exhaust and cooling jacket (hot water) and used to generate cooling.
  • Capacity range without fuel firing: 50 – 3500 TR
  • Capacity range with fuel-firing option: 50 – 1350 TR

Thermax Heat Pump

  • Heat-pump absorption units take in high-grade heat and use it to generate lower-grade heat that can be used in traditional heating systems. Typically, with the input of 1 unit of high-grade heat, a heat pump can generate 1.7-1.8 units of lower-grade heat.
  • Heat Source:
    • Dry saturated steam: 30 – 145 psi
    • High-temperature hot water: 280 – 360o F
    • Exhaust gas: 520 – 1,100o F
  • Capacity range: 1,700 – 68,000 MBH
  • Heating COP: 1.7 – 1.8

Thermax Ice Making

  • Thermax absorption chillers can operate at process temperatures significantly below the capacities of traditional designs. In fact, their low-temperature chiller can supply glycol or anti-freeze solution at temperatures as low as 23° F. This makes it possible to utilize absorption-chiller technology to make ice for a more robust system.
  • This allows building operators to more effectively shift electrical demand.
  • Full absorption solutions and hybrid solutions that utilize a compressor are both available.


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