Results 1 to 13 of 13
  1. #1
    Join Date
    Apr 2005
    Location
    Central California
    Posts
    186

    Reinventing the wheel?

    Not sure what to think about this?

    Has anyone had any experience with this thing?

    Is this another Beacon disaster?


    http://www.ke2therm.com/files/B-1-1_Evap_Eff_sm.pdf
    Only Chuck Norris can slam a revolving door

  2. #2
    Join Date
    Oct 2004
    Location
    Central WA
    Posts
    1,473
    Interesting theory. I'd like to play with one. I don't know that I like cycling the evap fans so much. Also, I wonder what the actual energy savings is vs the cost of the controller.

    Don't get too comfortable with your old wheel, though. EXV's and Demand defrost are here, and its only a matter of time before they and other electronic controls are the norm vs the exception in commercial refer.

  3. #3
    Join Date
    Apr 2005
    Location
    Central California
    Posts
    186
    I say bring it on. I love technology and gadgets. Just make sure the crap works. You are right exv's and stepper motors and such have been around a long time. I don't know how many flowtronic exv's I have changed and how many beacon systems I see with the exv cut out and a txv thrown in with an a19. Pretty sad.

    Who knows when that new wheel will come around. I am 30 something and I would almost bet by the time i hand my co down there will still be good ol fashion kt 83's all over the countryside. Reliability is just not there yet in this exv stuff for refrigeration. I wish it were though. Get this stuff proven so the price would come down and get our equipment into the 21st century
    Only Chuck Norris can slam a revolving door

  4. #4
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    Fan cycling seems to be the primary source of energy savings.
    Fan cycling for holding product temperatures should work.
    When hot product is introduced, fan cycling would be detrimental to chilling the hot product quickly. This could create a quality and/or safety issue. Also products differ in water content. High water content is more likely to need constant fan until holding temperature is reached. I would want to see their strategy for various products and applications. How smart is it...really?
    Finally I wonder what effect this would have on humidty where meat or vegatables are stored exposed to the air.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  5. #5
    Join Date
    Jul 2011
    Location
    St. Louis
    Posts
    121
    In the interest of full disclosure, I am the Training Manager for KE2Therm Solutions.

    Fan cycling is not the primary means of energy savings for KE2Therm Evaporator controls. Fan cycling is used to recover the latent heat of the frost through sublimation. Figure 1 in the bulletin shows that the fans are cycled in a tighter temperature band than the compressor, saving energy by less compressor run time.
    Frost on the evaporator represents a waste of energy and shrinkage of product. Compressors must run to create the frost and, in traditional defrost methods, additional energy must be added to the space to melt and drain the resultant water. The fan cycling scheme constantly uses the latent heat of fusion of the frost to chill the room for "free".

    Fans blowing on fresh product can cause more shrinkage than cycling, this is the reason most service meat cases do not have fans, only gravity coils. Fan cycling stabilizes humidity by returning moisture to the room, and maintaining higher humidity prevents shrinkage or moisture from leaving the product.

    Since less frost is allowed to accumulate on the evaporator, fewer and shorter defrosts are required. This is the major means of saving energy for KE2Therm. In real world conditions, we have seen defrosts reduced to 3-5 defrosts per week, from 3 time based defrosts per day. Less defrost heat added to the space means the compressor does more of its work cooling the product, and less removing this additional heat. Hence shorter run times and energy use.

    Hot product may benefit even more from fan cycling. Warm, moist product creates even more frost, which needs more, and longer, defrost cycles. This additional defrost time extends pulldown time and creates more of a health and sanitary concern.

    Disabling the fan cycling is an option built into the controller, for those who are concerned about air stratification. However, doing so will sacrifice some of the system efficiency and product integrity the control is designed to deliver. An auxiliary temperature sensor can be connected to the controller to monitor a space temperature in areas where air stratification is a concern.

    This unique adaptive technology has been proven in over a decade of service in Europe and Asia, and KE2Therm Solutions is now bringing it to the United States.

    I invite everyone to visit our website for more technical and case study information or contact us at 636.266.0140.
    Last edited by k-fridge; 07-19-2011 at 10:19 PM.

  6. #6
    Join Date
    Apr 2005
    Location
    Central California
    Posts
    186
    Interesting product.

    Would this not be a good application in a high TD application where we are trying to remove humidity from a product using small coils with large hp compressors (relative to the evap rating. 15 degree TD for example)

    Nut storage for example. We want to keep the humidity low. You say you can turn the fan cycling feature off but in a high TD application frost is very hard to avoid.....
    Only Chuck Norris can slam a revolving door

  7. #7
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    Quote Originally Posted by BDOLIN View Post
    ....Since less frost is allowed to accumulate on the evaporator, fewer and shorter defrosts are required. This is the major means of saving energy for KE2Therm. In real world conditions, we have seen defrosts reduced to 3-5 defrosts per week, from 3 time based defrosts per day. Less defrost heat added to the space means the compressor does more of its work cooling the product, and less removing this additional heat. Hence shorter run times and energy use...
    The product brochure says that this device works on refrigeration and freezers. A frost cycle is assumed for both.

    For medium temp refrigeration, a defrost cycle using a low pressure switch on a properly sized evaporator works fine with zero defrosts. The cut-in temperature is set at 36 to 38°F and the cut-out pressure depends on the unique characteristics of the system and the product being cooled.

    I can see this working on medium temp, frost cycle applications, but I cannot see this being advantageous on a freezer application which by nature operates in a frost cycle to maintain temperature with a defrost cycle using external heat to defrost the evaporator periodically. The sublimation effect will occur on the compressor off cycle with or without fan cycling. I don't see the fan cycling greatly increasing frost sublimation during compressor off cycles.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  8. #8
    Join Date
    Apr 2002
    Location
    Ann Arbor, MI
    Posts
    2,986
    Quote Originally Posted by BDOLIN View Post
    In the interest of full disclosure, I am the Training Manager for KE2Therm Solutions.
    Brian, I'm happy to see another refrig intellect joining this fray.

    Quote Originally Posted by BDOLIN View Post
    I invite everyone to visit our website [URL="http://www.ke2therm.com"] for more technical and case study information or contact us at 636.266.0140.
    You're allowed to place your web links and contact info in your sig file, not in your posts. See User CP/Edit Signature link on this site. Non-commercial posts.
    If the only tool you have is a hammer, you tend to see every problem as a nail. – Abraham Maslow

  9. #9
    Join Date
    Jan 2006
    Location
    Near Atlanta, GA.
    Posts
    14,492
    We've installed three of them recently and so far I'm impressed. Two of them were to convert dead Beacon 1 systems that no longer have available parts.

    Beacon 2 has been solid equipment, BTW.

  10. #10
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,064
    Ive not seen this particular unit...but I've seen several others in field operation and I like them!

  11. #11
    Join Date
    Jul 2011
    Location
    St. Louis
    Posts
    121

    Hmm

    Thanks, Andy, for your guidance. I'll leave my salesman hat at home next time.
    As for intellect- when I stopped paying my Mensa dues they took my intellect back.

  12. #12
    Join Date
    Jul 2011
    Location
    St. Louis
    Posts
    121
    Quote Originally Posted by lynn comstock View Post
    The product brochure says that this device works on refrigeration and freezers. A frost cycle is assumed for both.

    For medium temp refrigeration, a defrost cycle using a low pressure switch on a properly sized evaporator works fine with zero defrosts. The cut-in temperature is set at 36 to 38°F and the cut-out pressure depends on the unique characteristics of the system and the product being cooled.

    I can see this working on medium temp, frost cycle applications, but I cannot see this being advantageous on a freezer application which by nature operates in a frost cycle to maintain temperature with a defrost cycle using external heat to defrost the evaporator periodically. The sublimation effect will occur on the compressor off cycle with or without fan cycling. I don't see the fan cycling greatly increasing frost sublimation during compressor off cycles.
    You have good observations.
    Although, perhaps not obvious, the greatest efficiency and energy savings are realized on freezers. “Forced” sublimation with fan cycling adds to the benefit by about 1200 BTUs of cooling per pound of frost used, but the method of defrost can provide greater savings. Demand or smart defrost based on loss of efficiency of the evaporator will lead to optimum defrosts over fixed time based systems.


    Cycling electric heaters during defrost also make a lot of sense. Since electric heaters heat different parts of the coil differently, the pause between heating cycles allows the heat to be distributed to all parts of the evaporator evenly. Not only does this prevent high temperature hotspots on the evaporator that can cause fogging, but effectively the heaters are only energized for about 60% of the time normally used with traditional methods. Sure, the defrost termination may be set for 35-45F, but it may take so long for the heat to get there, that parts of the coil may reach 150F! Water hitting these surfaces leads to fogging and frost on ceilings, floors and product. Some technicians add more and longer defrosts to compensate, adding to the problem rather then solving it.

    Any heat you put into the room during defrost must be pumped back out by compressor run time and energy use. Keep it cool, infrequent and short to gain the most efficient use of the evaporator and compressor.

  13. #13
    Join Date
    Jul 2011
    Location
    St. Louis
    Posts
    121
    Quote Originally Posted by mr kev View Post
    Interesting product.

    Would this not be a good application in a high TD application where we are trying to remove humidity from a product using small coils with large hp compressors (relative to the evap rating. 15 degree TD for example)

    Nut storage for example. We want to keep the humidity low. You say you can turn the fan cycling feature off but in a high TD application frost is very hard to avoid.....
    Thank you for your compliment.

    As you say, in a high TD application, frost would be difficult, if not impossible to avoid. In addition, if a low humidity is desired, full sublimation may not be appropriate. In that instance, some sort of smart defrost algorithm on the controller really becomes important.
    Traditional time based defrosts happen whenever the clock starts them, whether needed or not. Perhaps worse, not when needed to keep the coil clean. Without manually “pulling pins” the clock has no ability to adapt to changing atmospheric, product or utilization conditions.
    By constantly measuring TD, the difference between coil surface temperature and return air temperature, a performance profile of an individual coil can be generated.
    A controller can then be designed to defrost only when the TD departs from that condition by a calculated amount. As conditions change, the time between defrosts may increase or decrease but will always be done to optimize the efficiency of the coil. ASHRAE and others suggest that a 10%f loss of coil efficiency is the optimum place to start a defrost. Proper optimization will prevent excessive frost buildup. When not properly controlled, frost will build enough to require longer, more frequent defrosts,at best, and poor product temperature control and possible hunting and floodback from the expansion valve, at worst.
    Timeclocks do not have the ability to defrost at optimum coil conditions and even when temperature is terminated in the usual manner (Klixon) may not achieve a clean coil. TD, when measured properly and backed by some "smarts" can be extremely effective in controlling defrost and maximizing evaporator efficiency.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event