Lambda DX/DXU

Direct expansion air conditioning units with microchannel evaporators and dual refrigerant circuit



Reliable, efficient and flexible direct expansion cooling system

Lambda DX/DXU is the next generation direct expansion air conditioners family based on microchannel evaporator technology and designed for high availability applications.


With microchannel evaporators, the Lambda DX/DXU range offers the highest efficiency level available today, as well as a number of benefits, including reduced weight, smaller footprint, reduced refrigerant charge and predictable heat transfer performance.

Dual microchannel evaporators

Lambda DX/DXU air conditioning units based on newly developed microchannel evaporators with an advanced design that combines high-performance flat tubes, state-of-the-art airside fins and ultra low-pressure manifolds with integrated refrigerant distributors.


The unique geometry of the manifolds and refrigerant distributors make it possible to feed the microchannel tubes equally for evaporation and ensures consistent and predictable heat transfer. Vertically-oriented microchannel tubes allow free condensate water shedding.


In combination with doubled area A-shaped design, microchannel evaporators permit many benefits to be achieved, including low airside pressure drops, higher cooling capacity, remarkably less weight and reduced refrigerant charge.

Design advantages

The slim geometry of microchannel heat exchangers allows evaporators to be installed with double heat transfer surface compared to precision air conditioners with the same footprint.


Larger heat exchanger surface leads to much higher energy efficiency thank the lower airside pressure drops and reduced fan power consumption.


Lambda family of precision air conditioners takes the full advantage of microchannel evaporators and offer an ultimate energy efficiency not found in any other air conditioning systems.


During the design process, special attention has been paid to air distribution on the coil surface. An accurate airflow analysis by CFD simulation has been performed to achieve the best possible aerodynamics, maximum airflow efficiency, and the lowest possible noise emissions level.

Advanced fans


Lambda DX/DXU features new radial fans with unique blade geometry and offers increased airflow based on reduced size and wider efficiency range. In combination with EC-motors with integrated control functionality, a communication interface, and overtemperature protection, these fans provide unbeatable energy efficiency, maximum flexibility, and the lowest possible sound emission.

EC motor technology produces significant savings at both full load and part load operation. Lambda’s EC-motors are maintenance-free and have a longer lifetime in comparison to brushed motors.

Scroll compressors


The scroll compressors employed in the air conditioners' design are the result of large-scale research and development efforts underway since 1979. These efforts have led to the production of the most advanced scroll compressor design currently available for air-conditioning applications.


Dual compressor Lambda DX/DXU units are perfectly suitable for both constant heat load and variable heat load applications. The customers of Lambda DX/DXU systems with R410a optimized scroll compressors can benefit from the quiet operation, unmatched reliability and low operating cost.


Lambda DX/DXU precision air conditioning units feature two independent refrigerant circuits each connected to its own microchannel evaporator, thus allowing the maintenance tasks to be carried out with the cooling system at power.


Through the use of microchannel evaporator, the refrigerant charge of the Lambda DX/DXU air conditioners is significantly reduced in comparison to old-style fin/tube designs.


Each refrigerant circuit equipped with electronic expansion valve (EEV) which has the function of regulating and optimizing the refrigerant quantity to the evaporator according to current requirements. 


Lambda DX/DXU features a refrigerant leak detection system, which is becoming a high priority for many customers, especially considering the potential for loss if a major leak renders a cooling system inoperable.


All the components of Lambda’s refrigerant circuit are located within the separate compartment, thus allowing easy access for maintenance and servicing.


The control hub of Lambda air conditioners is a sophisticated processor with control logic specially developed for direct expansion precision cooling units.


Users can adopt various control strategies based on either continuous temperature control, or on-demand airflow control, or constant pressure control by maintaining a pressure differential between the cold and hot aisles.

Lambda DX/DXU air conditioning system provides precise and reliable control of indoor temperature, humidity, and airflow for proper operation of cooled facilities. In addition to the wide range of options, this gives our customers the flexibility to design solutions, matching increasingly complex requirements as closely as possible.


Lambda DX/DXU cooling solution provides the excellent balance of high predictability, high power density, adaptability, and the best overall TCO.


Cooling capacity



Up to 4.06



Fan type

Radial EC-driven

Heat exchangers


Evaporation control


Humidity control


Air filtration




Related products



Compact, space-saving direct expansion precision air conditioners equipped with microchannel evaporators characterized by high heat transfer performance. This range is well-suited for IT and telecom room installations

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Kaltra Innovativtechnik GmbH

Max-Reger-Str. 44
90571 Schwaig

+49(0)911 715 32021

VAT: DE300943964

Kaltra is a customer-focused developer and supplier of reliable, energy efficient thermal management equipment and solutions.


From the professionalism of our research and development engineers to the wide experience of our service team, we are dedicated to delivering you the best service possible.

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