HEATING/COOLING: Portable Chiller Uses VFD To Match Energy Use to Load

A first for plastics chillers saves energy and improves temp. control.

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Thermal Care, Niles, Ill., introduced the NQV Series portable chillers at NPE2015, touting their use of a variable-frequency drive (VFD) on the compressor, a first for portable chillers in plastics, the company maintains. The VFD creates what Thermal Care calls a virtual “variable-size chiller” that can change its capacity to match the load without using hot-gas bypass and running the compressor at full amperage.

Assuming typical running conditions, the incremental cost of the NQV Series can pay back in less than six months thanks to the chiller’s ability to vary capacity and energy consumption to match the actual demand without cycling or damaging the compressor.

According to Thomas Benson, Thermal Care president, a 10-ton chiller, for example, normally runs at full capacity, regardless of load. “Now, with VFD, if you have a 5-ton load, you’ll have a 5-ton chiller,” Benson said. “The energy is matched exactly to the load.” Citing Chicago and its utility rates of around 10¢/kWh as an example, Benson noted that the entire chiller pays for itself in around seven or eight years, beyond the incremental ROI after six months.

Besides energy savings, Thermal Care says the precise speed control of the VFD and an electronic expansion valve gives the NQV Series tighter temperature control. A 7-in. color touchscreen and PLC control with full system PID are standard, as are compact micro-channel condensers for minimized refrigerant charge and increased durability, and 24 VDC control to keep the control circuit free from AC interference.