VZH 4-11TR

More about the features of a VZH 4-11TR

Several specific aspects of the compressor design render advanced performance, such as:

Optimization for varying pressure ratios and modes
Small scrolls VZH feature Intermediate Discharge Valves (IDVs). The IDVs inside the small platform are decisive to the system efficiency.
The isentropic efficiency of a scroll compressor reaches a maximum at the built-in pressure ratio. When a compressor is operating below this built-in pressure ratio the efficiency drops due to overshoot: the discharge gas is at a pressure above the condensing pressure, the compressor over compresses the refrigerant.

The IDVs in the 4-11TR models partially avoid over-compression as they release the refrigerant before the built-in pressure ratio. This early release avoids efficiency losses due to overshoot and thus significantly enhance the energy efficiency for A/C systems at part-load conditions. The wide operating map makes the compressor suitable for very varied cooling and for heating applications, from 3 to 33kW^∗ of heating capacity.

*Conditions:

Evaporating temperature -7°C; Condensing temperature 50°C; Superheat 5K; Subcooling 5K

Permanent magnet motor
The efficiency comparison between asynchronous and synchronous motors shows instantaneously the great advantages obtained when using a permanent magnet motor technology with:

• Uniform motor efficiency in operation always above 92%. This leads to a lower power consumption,
• Coolant stays cooler: the motor being more efficient, it will transfer less heat to the refrigerant and thus enhanced the compression efficiency.

Wide capacity modulation
The inverter drive modulates the cooling capacity from 15% to 100% for VZH 4.7 TR and from 17% to 110% for VZH 8-11 TR with a single compressor, which is very relevant for a variety of demanding applications where low part loads are needed.

Compact and reliable design
The 5 compressor displacements have the same dimensions and a compact footprint. This allows a cost-effective and flexible design over a wide range of cooling capacities.

Furthermore, the IDVs significantly reduce the stress level on mechanical components at start-ups.