Dry expansion evaporator tubes (also known as DX evaporator tubes in the industry) are specifically designed for dry shell-and-tube evaporators. In a dry expansion evaporator, the refrigerant flows inside the tubes, while water or a secondary coolant circulates outside the tubes on the shell side.

Kenergy's DX evaporator tubes feature an internally grooved straight tube design. The spiral grooves on the inner wall continuously disrupt the two-phase refrigerant flow during evaporation, breaking the laminar boundary layer and significantly enhancing the tube-side heat transfer coefficient. Compared to smooth tubes, the heat transfer efficiency is improved by over 40% under the same refrigerant flow rate. These tubes are ideal for heat pump units, industrial chillers, and refrigerated air dryers.

Core Advantages

针对干燥膨胀条件的最佳化牙槽

专门设计的凹槽几何形状即使在低制冷剂质量通量下也能保持出色的传热性能，同时确保适当的油返回压缩机。

兼容多种制冷剂

优化了R134a、R404A、R407C、R22和其他常见制冷剂的槽参数。可根据要求为替代制冷剂定制匹配。

多启动线程选项

提供1、2、4、6和8螺纹启动，以满足不同操作条件下传热强度和压降的不同要求。

直管供应

标准长度为3-6米，提供定制切割到长度的服务，以满足您的特定热交换器设计要求。

Technical Parameters

Outer Diameter (mm)	Bottom Wall (mm)	Tooth Height (mm)	Number of Teeth	Helix Angle (°)	Weight (g/m)	Heat Transfer Area (m²/m)	Material
7.00	0.25-0.32	0.12-0.18	45-55	15-25	42-50	0.021-0.024	TP2, T2
9.52	0.30-0.40	0.14-0.20	50-65	18-28	52-62	0.025-0.028	TP2, T2
7.94	0.27–0.35	0.12–0.18	45-60	18>28	63–75	0.028–0.032	TP2, T2

Typical Applications

Air Source Heat Pump Evaporator

Dry expansion evaporator for air-to-water heat pumps used in residential heating, domestic hot water, and commercial heating applications.

Industrial Chiller Evaporator

Water-cooled and air-cooled industrial chiller evaporators for process cooling, precision machinery, and factory temperature control.

Refrigerated Air Dryer Evaporator

DX evaporator for refrigerated air dryers (cold air dryers) in compressed air systems to efficiently remove moisture.

Modular Air-Cooled Heat Pump

Multi-circuit evaporator for modular chiller and heat pump systems requiring compact heat exchanger designs.

Frequently Asked Questions

Q: What is the difference between tubes used in dry expansion evaporators and flooded evaporators?

In a dry expansion evaporator, refrigerant flows inside the tube and gradually evaporates along the tube length. The groove design must promote nucleate boiling while handling two-phase flow and increasing vapor quality. In contrast, a flooded evaporator has refrigerant on the shell side and water inside the tube, requiring enhanced boiling on the outer diameter. DX tubes focus on internal groove optimization for flow boiling, while flooded tubes typically have external enhancement for pool boiling heat transfer.

Q: How do internally grooved straight tubes ensure proper sealing after expansion into the tube sheet?

Our tubes have tight wall thickness tolerances of ±0.02 mm, ensuring uniform expansion into the tube sheet without excessive thinning or cracking. Consistent bottom wall thickness across the entire tube circumference and length guarantees a reliable mechanical rolled joint. For high-pressure applications, we recommend our O-annealed tubes, which provide optimal ductility for expansion. The groove geometry is designed to maintain structural integrity during expansion without groove collapse.

Q: How to match groove profiles for low GWP refrigerants such as R290 (propane)?

Compared to traditional HFCs, low GWP refrigerants such as R290 have different thermophysical properties and lower mass flow rates. For R290 and similar hydrocarbons, we recommend groove designs with lower fin heights and optimized helix angles to maintain efficient heat transfer under reduced refrigerant charge. Kaineng's engineering team can develop custom groove profiles based on your specific low-charge system requirements. We have successfully supplied DX tubes for R290 heat pump projects with a 40% reduction in charge.

Q: Can you provide anti-corrosion coatings for the tubes?

Yes, we offer several anti-corrosion treatment options depending on the application environment. For seawater or high-humidity applications, we can apply a specialized epoxy coating on the outer surface of the tube. To improve corrosion resistance in harsh water conditions, we also offer tin plating services. Please specify your water chemistry and operating conditions when inquiring, and our technical team will recommend the most suitable protective treatment.

Heat exchange tube for dry evaporator