- Liquid Cooling
- Pumped Two-Phase
- Custom Thermal, Fluid, and Mechanical Systems
- Liquid-Air HX
- Vaphtek® Environmental Control Units
- Tekgard® ECUs
- Tekgard® Chillers
The latest advancement in environmental control units, Advanced Cooling Technologies’ Tekgard® Vaphtek ECU combines two cornerstone technologies: standard vapor compression and pumped two-phase cooling. Designed to create an energy-efficient system that leverages ACT’s long-standing expertise in thermal management.
What is a Vaphtek® Environmental Control Unit?
Much like ACT’s standard Tekgard® ECUs, the Vaphtek™ Environmental Control Unit (ECU) is responsible for cooling the ambient air and returning it to the relevant space, which could include military and medical shelters, critical edge computing / IT shelters, base camps, ground support, command centers, emergency response shelters, and more. The Vaphtek® ECU is designed to be mobile, rugged, and durable, able to survive harsh climates and hostile terrain, just like our trusted Tekgard® brand, unlike traditional HVAC cooling solutions.
Unlike a standard Environmental Control Unit or ECU, Vaphtek® features two operational modes: (1) vapor compression (standard ECU) and (2) Pumped Two-Phase (P2P). The P2P or eco-mode will reject waste heat to ambient air, when cool enough, without requiring the high energy consumption of the compressor. Most climates will experience some level of energy, carbon emissions and/or cost savings, but certain climates such as Alaska could operate in eco-mode for > 60% of the year and save > $15,000 per unit in operational costs*.
*Nominal 72,000 Btuh ECU at 75% Load Capacity with Return Air = 85 °F. Based on 10 kW Generator consuming 0.5 GPH @ $10/gal in Normal vapor compression operation.
Standard Vapor Compression Mode
When the Vaphtek® Environmental Control Unit (ECU) is in medium to high ambient temperatures, it will operate in the standard vapor compression, or DX cooling mode. This is the standard operating mode for all Tekgard® ECUs.
In this mode, a compressor moves refrigerant between the evaporator and condenser coil, providing large amounts of cooling in any environment. This mode, however, comes at the cost of a higher electrical power input. This is illustrated in Figure 2.
Pumped Two-Phase Eco-Mode for Vaphtek® Environmental Control Units
Pumped Two-Phase mode is utilized when the ambient temperature drops below the desired indoor temperature; this offers the potential for free cooling. The Vaphtek® ECU automatically transitions into Pumped Two-Phase mode, turning off the compressor and energizing a pump that circulates refrigerant between the evaporator and condenser coils.
Since a pump is driving the cooling rather than a compressor, there is a substantial drop in the required electrical power, with tested units showing up to a 70% decrease in certain environmental conditions. When the temperature delta between the indoor and outdoor space is large, pumped two-phase mode can offer similar cooling capacities as vapor compression mode.
In addition, Pumped Two-phase mode uses refrigerant side economization, protecting the conditioned space from the outside elements, including dust, debris, and moisture.
ACT Vaphtek® Environmental Control Unit (ECU) Control System
The control system for Vaphtek® ECUs was created based on standard ECU operation but has been overhauled to include improved temperature control and an automatic mode that switches between vapor compression (DX) and Pumped Two-Phase (P2P) cooling. When in auto mode, the unit calculates the cooling demand on the ECU and determines if P2P can sustain the desired temperatures. If so, the unit will operate in P2P mode, allowing for reduced power consumption and cost savings. DX cool mode will be activated whenever the difference in temperature between the indoor and outdoor spaces cannot sustain sufficient Pumped Two-Phase cooling. These calculations are performed by an onboard PLC that continuously evaluates the environment conditions, supply and return air temperatures, empirical data and user input to determine the ideal operating mode. A simple diagram of the ACT Vaphtek® ECU control logic is shown in Figure 4.
Frequently Asked Questions
In a typical ECU system, the lowest MTBF component is the compressor. By running the compressor at a reduced rate, it should increase its longevity. The shortest MTBF component in P2P mode is the pump, which exceeds a typical ECU compressor and would also run at a lower rate than a single operation mode system. Maintenance frequency would be typical to most fielded ECUs of similar size.
The easiest path is to send ACT your use case and we’ll help you analyze if Vaphtek adds value. The savings realized are a function of the energy consumption difference between the compressor and pump and the climate (ambient air temperature), which dictates what percentage of time can leverage free cooling. Since there are standard compressor and pump sizes leveraged, there are many variables to analyze.
Yes, P2P is leveraged for many high-power density applications in military and harsh environment applications. Some examples include directed energy, phased array radar systems, medium and high voltage power electronics systems and battery cooling systems. Learn more about Pumped Two-Phase cooling in our learning center.
There is a transient response (seconds), but it would be negligible and unnoticeable to those in the shelter and/or would not cause overheating of electronics in IT or data equipment-heavy shelters.
Empirical data of a 6-ton system has shown up to a 70% reduction in power draw when transitioning from vapor compression (DX mode) to Pumped Two-Phase mode. Although this value will vary based on unit size and operating conditions, there are substantial power savings to be realized when there is a favorable difference in temperature between the indoor and outdoor space. Contact ACT for more information and a custom analysis of your application.
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