AKV 20-4 (042H2028) Danfoss Electric Expansion Valve

Product Overview

The AKV 20-4 (042H2028) is a high-performance, electronically operated expansion valve designed for precise refrigerant injection in commercial and industrial refrigeration systems. Operating on a Pulse Width Modulation (PWM) principle, the Danfoss 042H2028 (042H2028) serves a dual purpose: it acts as both an expansion device and a liquid line solenoid valve. This integration is vital for B2B applications such as large-scale supermarket refrigeration, cold storage, and process cooling, where tight superheat (SH) control is required to maximize evaporator efficiency and protect the compressor from liquid slugging. The "Type 4" designation identifies this as a high-capacity unit within the AKV 20 series.

Technical Configuration

The AKV 20-4 utilizes a specialized 13.5 mm actuator system, engineered to interface seamlessly with Danfoss ADAP-KOOL controllers. Unlike traditional modulating valves that change needle depth, the 042H2028 cycles fully open and fully closed at specific intervals; the flow rate is precisely managed by the duration of the "open" time. This design results in a robust, hermetic valve with fewer moving parts, capable of millions of cycles. Rated for a Maximum Working Pressure (PS) of 28 bar (406 psig), it is compatible with a broad range of fluorinated refrigerants (HFC/HCFC), ensuring versatility across modern cooling infrastructures.

Technical Specifications

Technical FAQs

How does PWM control improve energy efficiency?

By using Pulse Width Modulation, the AKV 20-4 maintains a constant, high refrigerant velocity whenever it is open. This optimizes the heat transfer coefficient within the evaporator and ensures better oil return to the compressor compared to traditional mechanical valves that may throttle flow too low during low-load periods.

Does this valve provide a complete shut-off during power failure?

Yes. The 042H2028 is a Normally Closed (NC) valve. In the event of a power loss or when the controller reaches the setpoint, the valve closes hermetically, acting as a solenoid valve to prevent refrigerant migration.

Can this valve be used with CO2 (R744)?

The standard AKV 20 series is primarily designed for HFC/HCFC. For high-pressure CO2 applications, it is recommended to check the specific pressure ratings or look into the AKVH series, as R744 systems often exceed the 28 bar PS rating of this model.

Engineering & Installation Guide

• Filtration Best Practices: To ensure the longevity of the 13.5 mm actuator and the internal seat, a high-quality filter drier (such as Danfoss DML) must be installed upstream. Because the valve cycles rapidly, any solid debris in the liquid line can cause abrasive wear or prevent the valve from closing fully.

• Brazing & Thermal Safety: During the soldering of the inlet and outlet connections, it is mandatory to wrap the valve body in a wet cloth. The internal temperature must be kept below 100 Celsius to prevent damage to the precision-engineered seals and the actuator housing.

• Electrical Installation: The solenoid coil (sold separately) must match the controller's voltage (AC or DC). Ensure the coil is mounted with the cable entry facing downward to create a "drip loop," preventing condensation from traveling into the electrical actuator interface.