Results 1 to 8 of 8
  1. #1
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,347
    One of the things that attracted me to this new gig (art museum) I have (going on over four months now) was the opportunity to learn about equipment and systems that provide a precise level of temperature and humidity control. The museum, which has a vast photography collection, uses large refrigerated vaults to preserve the photographs, some of which are many decades old and irreplaceable if damaged. The equipment featured in this post is for the cold storage vault, which contains color photographs and negatives that through research has been shown to be best preserved at a temperature of 20F and 30% relative humidity.

    My boss, who has been at the museum since it reopened after a major renovation over four years ago, has been instrumental in getting this equipment dialed in from startup to today. He's quite pleased with the equipment's quality and performance and thought it merited inclusion in the Wall of Pride.

    This first pic is of the Partlow combination chart recorder and temperature/humidity controller. The chart records for seven days; there is nearly a straight line for both temp and humidity, consistent with the numbers displayed in the red LED (20 degrees/30% RH). The Partlow controls a Munters air handler, a Drake liquid cooled chiller, and an air cooled DX unit that acts as a second stage to knock the discharge air temp down enough to achieve a 20 degree setpoint within the vault.
    Dehumidificationm, in addition to two cooling coils, is accomplished by a dessicant wheel in the Munters AHU. This wheel is constantly reactivated by a blower passing heated air over the top portion of the wheel.






    These two control boxes contain the components necessary to run the Munters air handler blower, dessicant wheel, and reactivation fan and heater elements.





    This the right half of the Munters AHU. It is so long, it requires two photos to take it all in! A large reason for its length is the level of air filtration required for preservation of the photographs. The air filtration includes pleated, HEPA, Varicell, and carbon filters. Return air from the vault enters the AHU from the right, passes through the lower section of the dessicant wheel, then moves on through the series of filters and a chilled water coil before entering supply ducting.
    In the middle of the pic is the chilled water storage tank and pump for the Drake chiller, which sits behind the tank.





    Speaking of tanks, the sheetmetal used on the Munters AHU is thick. The entire array is built like a tank and has both a look and feel of quality. You can climb over this unit and the cabinet does not dent, bow, or even flex under your weight. Try doing that with most resi or light commercial split system AHU's!
    Here's the second half, showing most of the housing for the various types of air filters.





    Last but not least, the main workhorse of heat rejection for the vaults, a Drake chiller. This water cooled system uses a Copeland scroll compressor running R22. When online, the chilled water supply from this unit is below twenty degrees. The water that passes over the liquid cooled condenser gives up its heat to chilled water from the museum's central plant.
    The compressor runs so cold on the Drake, it had to be insulated to prevent the shell from becoming a solid block of ice.



    Not shown is an air cooled DX split system that is the final cooling element to get the vault down to twenty degrees.
    As for any possible defrost issues with a system running this cold, when a proper reactivation is done on the dessicant wheel prior to starting or restarting the chiller, the cooling coils will NOT frost at all, due to the very low humidity levels and dew points. Therefore there is no need to stop the system occasionally to defrost both the chilled water and DX evap coils. This allows the system to run non-stop 24/7, rendering a precisely controlled environment, optimal for the preservation of the artwork.


    [Edited by shophound on 10-26-2005 at 09:28 AM]
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  2. #2
    Join Date
    Aug 2003
    Location
    Ft Worth Tx ( North Richland Hills)
    Posts
    2,143
    Thanks, Shoppy....

    10 tons of cooling equipment for a 150 sq ft room. The desiccant wheel adds a helluva heat load. The glycol in the chilled water circuit cuts efficiency too. Proportional control of the 3-way chilled water valve is how a very stable temperature is provided. Humidity control is also proportional. The return air is routed through or bypasses the desiccant wheel by a face and bypass damper arrangement.

    The 60 degree/40% RH cool vault for black and white negatives and photos is quite a bit larger.... 600 sq ft.

    Humidity contol is more important than the temperature control....any condensation on the prints and negatives...let's just say I'd be lookin for a new challenge elsewhere. and thanks for all not commenting on Shoppy's post at once. It gets so chaotic when that happens.



  3. #3
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    I need to come visit some time this winter. I have almost no interest in the art, but I want that tour of the mechanicals I was offered.

    If I had been now where I was 5 years ago, you would have had some more competition for that job shophound.
    If more government is the answer, then it's a really stupid question.

  4. #4
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    Originally posted by shophound
    Return air from the vault enters the AHU from the right, passes through the lower section of the dessicant wheel, then moves on through the series of filters and a chilled water coil before entering supply ducting.
    Is the return air filtered before the dessicant wheel?
    If more government is the answer, then it's a really stupid question.

  5. #5
    Join Date
    Aug 2003
    Location
    Ft Worth Tx ( North Richland Hills)
    Posts
    2,143
    Hi Mark...... The invitation is still open. There's a 2" pleated filter upstream of the desiccant wheel. It is kinda odd that the others are on the discharge side of the supply fan. The vault itself is like being inside of a walk-in cooler. Has the same heavy doors as a walk-in cooler. Very little people traffic in the vaults , so there's not much dirt and dust introduced into the vaults and they are sealed and insulated pretty tight. All the air handlers in the museum have more banks of filters than an average commercial air handler.

    Here's a statistic.... there's over 1000 carbon filters in the building with an average weight of 12 lbs each.... 6 tons of carbon filters and our cost is $45,000 for a carbon filter change. Fortunately they last about 3 years between changes.

  6. #6
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,347
    Thanks, Shoppy....
    No sweat, Zone. (oops, pardon the pun)


    Originally posted by mark beiser
    If I had been now where I was 5 years ago, you would have had some more competition for that job shophound.
    I'm sure you would've been good competition, judging by your posts.
    Come on by for a visit when you can. I've been here over four months now and I still learn new stuff about the mechanics of this place all the time.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  7. #7
    Join Date
    Nov 2005
    Location
    cairo -egypt
    Posts
    24
    I HAVE A CHART RECORDER FOR temperature IN MY CENTER TOO..
    GOOD JOB IAM SURE YOU ON TRAC..
    Together we can improve our business

  8. #8
    Join Date
    Oct 2004
    Posts
    1,722
    I've never seen anything like this before. Very interesting.

    Thanks for the pics and description.

    BTW...great work.
    Get back to work.

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