Thinking Outside the Box (February 2000)
But these engineers will also agree that the perception is too often true, as many in the engineering world often take the path of least resistance, offering up the same chiller design time and again without looking at other options. Others argue that liability issues, time constraints, and improper fee structures mean the words “innovative” and “engineer” can never be used together.
New Technology Leads to InnovationIt used to be that innovative design wasn’t even considered when planning a chiller system, because engineers had little choice in the types of chillers they could offer. A system would usually be designed around either an R-11 centrifugal chiller or an R-22 reciprocating chiller. Nowadays there are multiple choices in refrigerant and compressor type, and certainly multiple choices in drivers.
Jim Porath, district sales manager for the Twin Cities office of York International, Minneapolis, says that engineers can choose from standard electric drive chillers, variable-speed electric drive chillers, gas engine- driven chillers, single-stage absorbers, dual-effect absorbers, and steam turbine centrifugal chillers. “There’s a wide range of choices that can work in different buildings and different building types,” he noted.
And chillers can be massaged to fit a particular application. For example, one of Porath’s customers decided to use a gas turbine to drive a multistage centrifugal chiller. “The concept of using a gas turbine to drive the compressor isn’t new. But in an air conditioning application, it is unique.”
The engineer involved with the project, Gary Gustafson, director of engineering for Minneapolis Energy Center, Minneapolis, says the technology made sense for this particular application. The project involved related district cooling companies San Diego Power and Cooling and Minneapolis Energy Center, under the umbrella of NRG Energy, an international energy company.
“The impetus behind this project was to get a direct gas-driven chiller installed vs. the electrics that were already there to get operating costs down,” says Gustafson. He adds that the turbine manufacturer, Solar, San Diego, along with York, came up with a plan for a gas turbine-driven chiller with a nominal rating of 2,250 tons.
The system also includes a heat recovery system on the gas turbine, which in turn drives a 500-ton absorption chiller. That chiller helps create additional cooling and also increases the efficiency of the system while keeping operating costs down. The system also needed additional pumping modifications in order to pump chilled water to the downtown area, so secondary pumping was put in at the same time. All this had to happen within an existing plant with a small area, so the whole project was quite complicated both in terms of schedule and space.
Gustafson says that he’s lucky that he’s able to be more innovative in his position, and he’s always looking for new and different ways to apply chillers. “My personal philosophy is you really need to learn as much about a system in order to make an intelligent decision. Look at the big picture, not just the chiller, but also the overall system. You need to look at how the system is operated on an annual basis versus just the peak,” says Gustafson.
Less Means MoreWayne Dunn, P.E., principal, Sunbelt Engineering, Jacksonville, FL, is another engineer who thrives on doing things differently. He is just finishing up a project that involves a 30-plus-year-old, 11-story office building in Jacksonville. A critical requirement for this building is backup cooling, as a fourth floor computer room had to have guaranteed 24-hour cooling.
The client had planned to spend over $2 million in order to rebuild the entire chiller system, which consisted of two 754-ton chillers, one 250-ton chiller, and one 600-ton chiller, as well as four 100-hp motors, four 75-hp motors, and two 40-hp motors. Dunn originally planned to use three 400-ton chillers with two of the chillers having variable-frequency drives.
The more he thought about it, though, the more Dunn decided that it could be done differently and for less money. Scrapping his original plan, he started over, reworking the design until he finally came up with a variable flow, primary loop-only chilled water system using a two-way valve and a bypass. The new system consists of two 600-ton dual compressor McQuay chillers, two 75-hp motors, and two 50-hp motors.
“This is a more cost effective approach than using primary/secondary chilled water or using variable-frequency drive compressors with multiple chillers. It’s also cheaper to use two chillers rather than three,” says Dunn. The finished project wound up costing less than $1.3 million – significantly less than the $2 million the client intended to spend.
Tom Watson, chief engineer, McQuay Chiller Products Division, Staunton, VA, says Dunn was very innovative in the way he handled the piping and vfd’s. “He adapted the existing piping and used vfd’s with a single loop rather than a primary/secondary loop. That’s a major energy savings, because the pumping power is a major part of the annual energy use.”
Dunn also specified a comprehensive digital controls system but notes that interoperability – or lack thereof – is continuing to be a problem. “We ordered the chiller open protocol to the controls system and the controls system open protocol to the chiller, but it’s still a problem. I wanted open protocol, and we didn’t receive it. And as an industry, we’re not a lot closer to it than we were before – we just know what the words mean now.”
Motoring Toward InnovationThere are also innovations taking place in the manufacturing facilities sector. Plant Engineering and Design Service Inc. (PEDSI), Liberty, SC is a design-build mechanical construction firm that specializes in custom-engineered hydronic heating and cooling systems for industrial processes. The firm’s president and chief engineer, Dave Autrey, P.E., says that meeting tight budgets and deadlines has become a way of life for his firm. The mission of PEDSI is to live within those restraints while delivering exceptional value to their clients through the application of innovative engineering and construction techniques in its turnkey projects, he says.
Recently Autrey and his firm were involved in designing and constructing a new, central, chilled water generating and distribution system to serve the hvac and process needs of an automotive parts manufacturer. Those needs had to be met in the existing plant, as well as in the new 50,000-sq-ft expansion, all within the parameters of a tight budget and an accelerated construction schedule. The challenge also included the design and construction of an hvac system for strict temperature and humidity control in the expansion.
PEDSI came up with a chiller plant that utilizes an all-primary, variable volume, variable-speed chilled water distribution system. The lower first cost of this design is further enhanced by its superior owning and operating cost as compared to a primary/secondary design. This particular system incorporates two existing, relatively new Carrier “Evergreen” R-134a chillers of dissimilar size, one of which was relocated to the new chiller room, and one of which remains in its original location – remote from the new chiller room.
The remotely located machine is piped into the chilled water return and supply headers, so that it functions as if it were located in the new chiller room. Two additional new Carrier Evergreen R-134a chillers of a larger size are included in the current operating system. Block valves for two future chillers have been installed, and the chilled water and condenser-piping layout for these chillers has been completely designed.
All chillers, cooling towers, and pumps are “headered,” so that any combination of equipment can be operated as needed to offset the system load, and so that maximum redundancy is achieved with a minimum of capital equipment. The control system ensures that chilled water flow in each of the on-line evaporator circuits is maintained at the same gpm/ton so that regardless of the combination of on-line chillers or the system load, each chiller operates at the same percentage of its respective design capacity. The system is currently capable of providing 1,600 tons of cooling capacity. The addition of the two planned, future chillers will boost system capacity to 2,700 tons.
The control program for the system proved to be the greatest challenge. The chiller plant utilizes Carrier’s “CCN” control system. Autrey labored many hours with Carrier senior control technician, Tom Strawder, under a mutual nondisclosure agreement between the two parties to develop the required custom algorithms. Strawder was instrumental in helping the owner to realize a very significant savings in installation cost without sacrificing system reliability or operating cost.
Wayne Vafiadis, sales engineer, Carrier Commercial Service, Greenville, SC, also worked with Autrey on the application. “Since this is a primary variable-flow system, we had to work very closely with Dave on the minimum flows required through the chillers. He worked out the control scheme, because with the different size chillers, it’s hard to balance flows. There are different pressure drops through smaller machines versus larger machines, so we had to make sure we didn’t go below the minimum flows on any of the chillers.”
Obstacles to InnovationNot everyone wants to be an innovator, as there are definite risks to being the first one to try something. As the old adage goes, the pioneers are the ones out front with their faces in the sand and arrows in their backs. Many engineers don’t want to be in this position. Some claim that creating an innovative design can lead to complicated maintenance, which could lead to a system not being maintained at all.
As Autrey notes, “Fewer and fewer personnel are being allocated to maintain these larger systems. We continually fight the battle of trying to automate a system to the extent that the requirement for operator interface is minimized, versus not making the system too complicated to master in the relatively few man hours that the facility operations staff can dedicate to the task of learning the system.”
Dunn adds that the remaining maintenance personnel are usually not paid that much and yet they’re charged with looking after millions of dollars of equipment. Often these people receive very little training about the equipment they’re operating, or sometimes they just can’t comprehend how a system works. “We can factually prove that it is less expensive to invest in your people than it is to invest in resolving issues where people don’t know what they’re doing. That’s true with respect to fees, and it’s true with respect to maintenance dollars,” says Dunn.
Speaking of fees, that’s probably one of the biggest obstacles to being innovative. Engineers are under huge cost and time pressures today. On the time side, Porath notes that it used to be that projects evolved over several years. “Today, everything is done so fast track that the combination of lack of time to design a project and the cost pressures lead engineers to be frustrated that they don’t have the time and the financial resources to think outside that box. It isn’t that they’re lazy, it isn’t that they don’t want to do that. They just don’t have the time or the proper fee structure to allow them to really investigate deeply these new technologies.”
Dunn calls this problem “the hard facts about soft costs.” He says that most engineers just don’t charge the right amount for their hard work, and since being innovative means more liability and more exposure, why would anyone want to be innovative?
“I charge a lot for my services,” says Dunn. “I have a limited number of clients, and we’re a small firm. I don’t work the traditional way, and I don’t go after the regular government work. I get to be innovative a lot, and I make money by being innovative. The clients allow me to do that because I save them money, so they’re willing to invest in my time. Innovation reduces both the capital cost and the life cycle cost of the project.”
Dave Kreinest, vice president of facilities, Trammell Crow, Jacksonville, is one of Dunn’s regular clients and a believer in innovation, providing it yields lower costs to the client. It was Kreinest who allowed Dunn the opportunity to rework the office project discussed above, for which Dunn is very grateful. “My clients trust me,” he notes, “and they keep me busy.”
Dunn adds that if he didn’t charge more for his services, there would be no way he could come up with many different variations on a design. “If I went the traditional route and reduced the cost to the owner, my revenue would go down because I’m getting paid a percentage of what the cost of the project is. Instead, I decide to be innovative, so it takes me two or three swipes at it before I get something that I am satisfied to put my P.E. on, so my soft costs have to go up in order for the hard costs to go down.”
He adds that charging more is the only way an engineer can be innovative. “Provide real value to your customers. Create an understanding between you and your customers as to where the value is in your services.”
Autrey acknowledges that a lot of stiff competition exists in this industry. He states that his firm strives to forge long-term relationships with their clients based on integrity, technical competency, and quality of workmanship. “That simply takes a lot of hard work over a sustained period of time,” he says. In the final analysis, however, Autrey advises, “Put your house and your cars in your wife’s name. Then just do it. The worst they can do is sue you.” ES