AKV 20-4 (042H2027) Danfoss Electric Expansion Valve

Product Overview

The AKV 20-4 (042H2027) is a high-capacity, electronically operated expansion valve designed for precise liquid injection in industrial and commercial refrigeration plants. Utilizing the Pulse Width Modulation (PWM) principle, the Danfoss 042H2027 (042H2027) functions as both an expansion device and a liquid line solenoid valve, providing a tight shut-off when de-energized. This dual-purpose design is essential for B2B industrial applications such as large-scale cold storage, industrial chillers, and supermarket rack systems, where maintaining an exact superheat (SH) is critical for energy efficiency and compressor safety. The AKV 20-4 is engineered to provide higher mass flow rates than the AKV 20-1/2/3 models, making it suitable for high-output evaporator units.

Technical Configuration

The AKV 20-4 is built around a robust 13.5 mm actuator system and is typically driven by a Danfoss ADAP-KOOL controller. Rather than modulating the needle position, the valve cycles fully open and fully closed; the flow rate is determined by the duration of the "open" phase within the cycle. This mechanical simplicity results in a hermetic construction capable of withstanding millions of cycles without degradation. With a Maximum Working Pressure (PS) of 28 bar (406 psig), it is compatible with a wide range of HFC and HCFC refrigerants. The "Type 4" designation represents the specific high-capacity orifice size within the AKV 20 series framework.

Technical Specifications

Technical FAQs

What are the specific advantages of PWM control for high-capacity systems?

In high-capacity systems, PWM control ensures that when the valve is open, the refrigerant velocity remains high. This assists in efficient oil return to the compressor and optimizes heat transfer within the evaporator by maintaining a consistent turbulence level, which is often superior to the partial-throttling found in mechanical valves.

Is an additional solenoid valve required for system safety?

No. The AKV 20-4 is a Normally Closed (NC) valve that provides a reliable, hermetic seal when the power is removed. This eliminates the hardware costs and pressure drops associated with installing an extra solenoid valve in the liquid line.

Can the internal orifice be replaced?

The AKV 20 series features a modular design where the orifice and needle assembly can be serviced or replaced if necessary, ensuring the valve body remains in place while restoring the valve to its original factory performance.

Engineering & Installation Guide

• Upstream Filtration: Due to the rapid cycling nature of PWM valves, it is mandatory to install a high-quality filter drier (such as the Danfoss DML or DCL series) immediately before the valve. Debris in the liquid line can cause rapid wear on the valve seat or prevent the needle from sealing properly, leading to "flooding."

• Brazing Thermal Protection: During installation of the solder connections, the valve body must be protected from excessive heat. Wrap the body in a wet cloth and ensure that the temperature of the 13.5 mm actuator housing does not exceed 100 Celsius. Overheating will damage the internal seals and the coil interface.

• Electrical Configuration: Ensure the coil voltage matches the output of your Danfoss AK-CC or AKC controller. The coil must be mounted with the cable entry pointing downwards (creating a drip loop) to prevent moisture from traveling along the wire and into the actuator assembly.