Next-generation dryer technology can improve car wash performance, cost & efficiency

by David Dougherty

Let’s face it, when drivers pull into an in-bay automatic car wash, they have two simple goals in mind: 1) to drive away in a clean car, and 2) to drive away after the shortest passage of time possible. In the past, that goal, when considering the time factor, was sometimes compromised by the drying system that awaits drivers once the washing and rinsing cycles have been completed.

You know the drying drill, replete with a 30- or 60-second countdown clock that challenges drivers to maneuver through the dryers placed above or along the side of the exit door, hoping to time their departure with the exact moment that last blast of air removes the final drops of water from the back of their vehicle. Yes, to some, the car wash drying process was a necessary evil, as no one wants to leave the wash bay with a car spotted with beads of water while, on the other hand, the time it took to complete the drying process—which was oftentimes never entirely thorough enough to begin with—was seen as a detriment.

Thankfully for car wash operators and their customers, those days of extended drying processes are coming to an end. This article will take a look at the new technology that is making the drying process more efficient and timely for the operator and driver, while also providing bottom-line benefits for the operator in terms of reduced utility, equipment and maintenance costs.

Turning Drying Into a Breeze

In addition to the timeliness issue, legacy drying systems also suffered from performance problems, as well. Simple physics reveal that when the drying air exits a dryer, its highest and most effective rate of speed occurs immediately at the exit point. From there, the air stream loses much of its velocity as it meets the resistance of the surrounding air. Therefore, by the time it reaches the vehicle, air flow has been minimized, meaning that the optimum drying air flow rate is occurring well before it ever has a chance to meet the vehicle.

Recent advances in dryer technology have helped eliminate these air-flow concerns, however. Many next-generation drying systems now feature innovative designs that use concentrated air columns, a process called “air drafting” and an optimized array of blowers to deliver high-speed air to the vehicle’s surface.

Concentrated air columns work on common principles. For example, to increase the rate that water exits a garden hose, you concentrate the water stream. Or to increase the brightness of a flashlight, you concentrate the light beam. Concentrated air columns are achieved by using round discharge nozzles at the bottom of the dryer outlet. These round nozzles are more effective than square or rectangular nozzles because they do not tend to break up air flow, enabling the air’s velocity to stay concentrated longer, meaning it meets the vehicle’s surface at a higher rate of speed, which results in the increased removal of any remaining water.

Air drafting is a technique that is used by racecar drivers. It literally splits the air, meaning there is less air turbulence through which the vehicle needs to be driven. In a dryer system, air drafting is created through the use of multiple blowers that combine to lessen wind resistance. A typical air-drafting blower system may consist of four 7.5-horsepower stationary blowers with two center blowers that are positioned over the vehicle. The first blower does the job of “breaking” the air, which reduces the amount of wind resistance that the trailing blower experiences. The trailing blower, which is now unencumbered by excessive wind resistance, can then work on removing the water on the vehicle’s surface. Side blowers that use these air-drafting techniques can also be added to further increase drying effectiveness.

Another advancement in dryer efficiency is found in the strategic positioning of the blowers. Simply put, blowers that are positioned as close to the vehicle as possible do a better job moving water quickly off the vehicle’s surface. When water droplets move on a vehicle, they split. The more they split, the smaller they become. Unfortunately, these smaller water droplets are harder to move. Therefore, it is imperative to use blowers that are positioned to remove the water droplets when they are at their largest. Properly positioned blowers also make use of gravity, funneling the water droplets down the sides of a vehicle, not forcing them to travel up and over the top.

One of the latest developments in understanding how dryers interact with the water on a vehicle’s surface combines the final rinse and drying processes into one co-dependent step. Working on the simple theory that it is easier to remove water that is already moving, while the final rinse is being performed, the dryers are simultaneously activated. This combined rinsing-and-drying process, often referred to as Flash Dry, can be completed in as little as 10-15 seconds, which allows the operator to meet the two main goals of the car washer: leaving with a clean, dry vehicle in an optimized amount of time.

Teaming Technology With Technology

With utility and maintenance costs rising, car wash operators need to find ways to not only give their customers the service that they demand, but they have to do it in a way that won’t have a deleterious effect on the bottom line. Thankfully for them, car wash manufacturers have begun creating all-electric vehicle wash systems that remove noisy, inefficient hydraulic motors from the operation. Instead of hydraulic principles, these systems use electric motors to provide the motion that the equipment needs to clean and dry the vehicles.

As a further benefit, many of these motors can now be controlled by simple and efficient variable frequency drives (VFD). A VFD is a system for controlling the rotational speed of an electric motor by controlling the frequency of the electrical power supplied to the motor. When a VFD starts a motor, it uses low frequency and voltage, which eliminates the enormous current in-rush that occurs when a motor is started with a motor starter. As the VFD begins operating, the frequency and voltage are increased at a controlled rate, allowing the motor to ramp up to the required operating speed without drawing excessive current. With a VFD, the stopping sequence is reversed, with the frequency and voltage ramped down at a controlled rate, instead of it being cut suddenly and sending harsh electrical noise throughout the power system.

In addition to the energy savings that is realized, all-electric tunnel systems have several other maintenance-related benefits. By using a VFD, control motors and the complete drive system benefit from “soft” starts and stops. Controlled acceleration and deceleration make all mechanical components last longer by reducing hard, “jolting” starts and stops. There is reduced motor vibration that works to increase equipment operation and longevity.

In 2009, the International Carwash Association (ICA) produced a white paper titled “Managing Power with Variable Frequency Drives.” The main point of the paper is that it makes no sense for car wash operators to run the motors of their wash systems at 100 percent capacity 100 percent of the time if only 50 percent of capacity is required. With that in mind, the ICA pointed out that “car wash dryer fans, pumps and compressors offer some of the greatest potential savings” through the use of VFDs. In fact, according to the ICA, “a dryer fan that is operating at 50 percent speed will ideally draw 12.5 percent shaft power.” This is a tremendous power reduction, which equates to enviable cost savings. Combined with the elimination of demand spikes, as well as the reduction in electromechanical torque stress being put on the drying equipment, the use of VFDs in the drying process can result in “lowering utility demand rates and increasing the longevity of electrical and mechanical components.”

Considering how many times per year the dryer speed could be throttled back between car washes, it’s easy to see that VFDs can be a powerful money- and maintenance-saving technology in the arsenal of the car wash operator.

Conclusion

While emerging with a clean car is the top concern of car wash customers, an effective, timely drying process will also score points and make those drivers more likely to return to your site. With the advances in dryer technology, as well as the availability of studies that highlight the effectiveness of new technologies like variable frequency drives, the car wash operator has never been better equipped to offer his or her customers the best in drying options.

David Dougherty is the senior product manager for in-bay automatics at PDQ Manufacturing Inc., De Pere, Wisc. PDQ Manufacturing is recognized as the technological leader in vehicle wash systems, providing superior quality, outstanding support, and products that contribute to its customers’ profitability. Brands include WashTools Conveyorized Tunnel Systems, LaserWash^® In-Bay Automatics, Tandem^® RiteTouch Vehicle Wash Systems, Access^® Customer Management Systems and MaxAir™ Dryers. Products are sold and supported worldwide through an extensive distribution network. For more information, visit www.pdqinc.com or call 800.227.3373. David can be reached at David.Dougherty@pdqinc.com.