R290 (propane) variable-speed compressors are the “future of light commercial refrigeration,” according to Huayi Compressor Barcelona (HCB), a Spanish manufacturer of hydrocarbon-based hermetic reciprocating compressors.

Compared to even high-efficiency fixed-speed (on/off) compressors, the manufacturer has found its propane (R290)-based variable-speed technologies can help reduce the energy consumption of refrigeration appliances by up to 12% compared to its R290 high-efficiency fixed-speed compressors.

HCB has also found that the inverter technology used in variable-speed compressors can enhance internal temperature control, extend component lifespan and create a more standardized supply chain since one model can serve a wider range of applications than a fixed-speed alternative.

The many benefits of inverter technology were presented by Pedro Olalla, HCB’s Sales, R&D and Quality Director at the ATMOsphere (ATMO) Europe Summit 2023, which took place in September 2023 in Brussels. The conference was organized by ATMOsphere, publisher of Hydrocarbons21.com.

Across all its brands, including HCB, China-based Huayi Compressors manufactured 72 million units last year, according to Olalla. HCB serves the light commercial sector under the Cubigel Compressors brand, with a focus on propane and isobutane (R600a) models.

HCB showcased its fixed and variable-speed compressors last week at the AHR Expo show in Chicago, its first appearance since 2018. “We are targeting the [light commercial] U.S. market,” said Olalla. “We have some presence in the U.S. but not like in Europe, Latin America and Asia.”

Energy savings

During his ATMO Europe presentation, Olalla shared findings from a study conducted by HCB and Turkish appliance manufacturer Ugur Refrigeration.

In the study, HCB compared its first-generation NVT70FSC variable-speed compressor, which was launched in 2020, with its high-efficiency NUT70CAb and NUS70NA fixed-speed models to assess how the different technologies impacted the performance of a 400l (105.7gal) ice cream freezer. All three units, as well as the ice cream freezer, use R290 as a refrigerant.

“We found that performance of the three compressors is very similar in terms of temperature,” Olalla said. “The main difference is the energy consumption.”

The results showed that HCB’s NUT and NUS compressors consumed 1,710kW and 1,639kW per day, respectively. This 4.2% reduction between the two models is in line with their COP – 1.8 and 1.88, respectively.

Meanwhile, the manufacturer’s NVT variable-speed compressor, with a COP of 1.83, consumed just 1,512kW per day. This reduction represents energy savings of around 11.6%, compared to its NUT model, and 7.7%, compared to its NUS model.

“Even with a lower COP, the variable-speed compressor produces energy savings compared to the more efficient fixed-speed unit,” he explained. “The advantage here is that variable-speed compressors can run at a lower speed for longer, producing a consistent temperature but with lower energy consumption.”

“Even with a lower COP, the variable-speed compressor produces energy savings compared to the more efficient fixed-speed unit.”

Pedro Olalla, Huayi Compressor Barcelona

He noted that the test was conducted in an ambient temperature of 25°C (77°F) and an internal temperature of −18°C (−0.4°F), and, besides the compressor, no other components or variables were changed.

Results were obtained in drop-in mode, in which the compressor speed is determined by the inverter according to variations in thermal load, added Olalla.

Alternative programming modes for Huayi’s variable-speed compressors are frequency mode, where the compressor is controlled by a frequency signal sent from the driver, and serial mode, where it is controlled by an external controller.

“Drop-in mode is the cheapest method as no additional equipment is needed,” Olalla said. “Just replace an appliance’s fixed-speed compressor with a variable-speed unit.”

Economies of scale

While variable-speed compressors are more expensive than fixed-speed alternatives, they often have lower operational costs thanks to reduced energy consumption.

In addition to minor updates to product design, upfront costs can be reduced though economies of scale as manufacturers increasingly opt for variable-speed technologies, said Olalla.

“Over the last few years, the cost [of variable-speed compressors] has reduced considerably, and I think this will continue as [demand] grows,” he added. “This has already happened in the domestic appliances market.” At AHR Expo, he noted that, while in the past there was a 100% difference in price between variable- and fixed-speed light-commercial units, the difference has shrunk to 50%. “With new regulations, sooner or later, everyone will move to variable speed,” he said.

A similar transition has also already been seen with regard to refrigerants, as manufacturers have moved away from CFCs, HCFCs and HFCs and toward hydrocarbons like R290 and R600a.

“For light commercial applications, natural refrigerants are the reality,” he explained. “About 70% of home appliances and light commercial use natural refrigerants, [and] it’s just a matter of time until all compressors use natural refrigerants.”

At AHR Expo, Olalla mentioned that all of HCB’s new development in light commercial compressors is for R290. All of its light commercial compressors are made in Spain and China.

“For light commercial applications, natural refrigerants are the reality. About 70% of home appliances and light commercial use natural refrigerants, [and] it’s just a matter of time until all compressors use natural refrigerants.”

Pedro Olalla, Huayi Compressor Barcelona