During the development period, Brown worked extensively with Danfoss and account manager Brian Kelley.
"You could buy a scroll compressor and an inverter off the shelf, but they won’t work as well together," says Kelley. "You need control logic and algorithms developed specifically for the system. Danfoss knows all about that, because we have spent years in our own extensive development process to get where we are today."
Kelley解释说,丹佛斯在1968年介绍了HVAC的第一个VFD。“VFD对操作变速压缩机至关重要,”他解释道。“它将提供给交流电机的电流的频率改变速度,扭矩和整体性能。这就是为什么在我们的表演者VRJ压缩机中使用的变频器内置了很多智能。”
The Danfoss variable frequency drive uses algorithms developed specifically for heating, ventilation and air conditioning (HVAC). Algorithms, which are programs that make decisions based on inputs and outputs, perform a number of jobs -- adjusting pressures and maintaining system stability as speed decreases and increases.
For the WaterFurnace 7 Series, a Danfoss VFD is paired inside the cabinet along with the Performer VRJ compressor.
"The Performer VRJ compressor is built in our Arkadelphia, Arkansas, plant," says Kelley. "As a variable speed scroll compressor, it operates through a range of high and low speeds, unlike one RPM for a fixed-speed scroll. Consequently, it can closely match the demands of the system to yield higher levels of energy efficiency."
Kelley explains that one challenge, however, is oil management. "As the scroll’s rotational speed changes, the amount of refrigerant — and oil — flowing through the compressor decreases. The VRJ compressor uses a patented oil injection system to ensure the scrolls and bearings are optimally lubricated at all compressor speeds.
“VRJ压缩机也是独一无二的,因为它可以run both slower and faster than what is standard. For example, it can turn down speed as low as 15 percent of its rated capacity and overspeed up to 117 percent from the nominal 3600 rpm. The overspeed capability means it can deliver more heat on colder days."
"The VRJ compressor allows us to do some unique things in equipment sizing," says WaterFurnace's Brown. "We can produce more heating capacity for a given home without increasing the length of buried loop. In technical language, it allows us to transfer heat from the earth loop — load it up between heating and cooling — more evenly. The result is higher heating capacity, which means lower operating costs and lower installed cost for the homeowner. This is a big advantage for areas north of the Mason Dixon Line and just south of the Great Lakes where we can take advantage of the loop balancing technique."
The ability to run the compressor, fans and pumps at slower than normal speeds brings another benefit — dehumidification. "The 7 Series has a special active dehumidification mode," explains Brown. "It turns the system into a whole-house dehumidifier, because the unit can dehumidify the home independently of whether it's heating or cooling. Most heat pumps will try to get moisture out of the air. But with our active dehumidification mode, the system can remove moisture without cooling or heating the home. Again, that means more comfort for less cost."
“我们的7系列地热系统如此干净整洁,这是令人难以置信的,”棕色强调。“People think it’s just too good to be true. The reality is, it is that good; it’s that efficient; it’s that simple; and we’re delivering that performance today."
– Bob Brown, vice president of engineering for WaterFurnace