The Challenge: Uneven Refrigerant Flow
In microchannel evaporators, cooling efficiency depends on how evenly refrigerant is distributed across dozens of parallel microchannels. When the refrigerant enters the inlet header in a two-phase state (liquid and vapor), the heavier liquid naturally settles at the bottom while the lighter vapor rises to the top.
This separation causes uneven feeding of the microchannels: some channels receive mostly vapor, others too much liquid. The result is reduced heat transfer efficiency, unstable operation, and significant performance losses.
In practical terms:
- Evaporators without any internal distributor can lose 25–35% of performance due to severe maldistribution.
- Systems equipped with conventional lateral-spraying distributors typically reduce losses, but still experience 10–15% performance degradation.
The Solution: Downward-Spraying Distributor (DSD)
To address this issue, Kaltra developed a new Downward-Spraying Distributor (DSD) architecture.
Instead of injecting refrigerant sideways inside the header — as in traditional designs — the DSD injects refrigerant vertically downward through precisely calibrated openings. This seemingly simple change produces a powerful effect:
- The downward spray works with gravity rather than against it.
- Liquid refrigerant is actively directed toward the lower region of the header.
- High-velocity jets create turbulence and fine mixing.
- Liquid and vapor phases are blended more evenly before entering the microchannels.
By mechanically disrupting natural phase separation, the DSD ensures that each microchannel receives a more consistent liquid–vapor mixture.
Near-Ideal Performance Achieved
Testing confirmed that evaporators equipped with Kaltra’s DSD technology demonstrate performance losses as low as 1–3%, approaching ideal distribution conditions.
The system also maintains high distribution uniformity:
- At coil inclination angles up to 30°
- At inlet vapor qualities below 0.4
- Under realistic operating and installation conditions
Compared to conventional designs, the DSD concept represents a major improvement in evaporator stability, efficiency, and surface utilization.
Raising the Standard for Microchannel Technology
By solving one of the fundamental challenges of two-phase refrigerant flow inside horizontal headers, Kaltra’s new distributor technology sets a new benchmark for microchannel heat exchanger performance.
The development reinforces Kaltra’s commitment to advancing thermal management solutions through practical engineering innovation and measurable performance gains.
Press Release Distributed by PRLog
Source: Kaltra GmbH
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