Many times a customer wants to age meat or cheeses at a specific temperature and humidity to prevent the food from “drying” out during the aging process. There are a couple of ways to approach it.
First one is a refrigeration system is installed to give the required capacity in the room and a humidifier is installed to temper or raise the air to the desired relative humidity level. This requires that the system has enough capacity to handle the sensible load on the room and all the latent load that the humidifier places on the refrigeration system. This can lead to a refrigeration system that is 2 to 3 times the actual load on the room. And depending on the size of the humidifier the refrigeration system can actually be overwhelmed by the humidity being injected which can cause the system to reach an equilibrium point somewhere in the range that is desired.
Another way to approach the system is to utilize a system where the dewpoint of the air is controlled by using either an EPR valve or a constant pressure expansion valve on the evaporator. By holding a constant evaporator temperature the coil will “wring” out any moisture in the air that is in excess of the desired point but not take any additional moisture out. This takes out the need for a humidifier to constantly put moisture back in the room to offset what is taken out by the evaporator.
Example: if the desired condition is 55 degrees/ 75% relative humidity the air in the room has a dewpoint of 47 degrees F and (.00687 lb/lb - moisture per lb of air). So if a coil is running at a SST of 47 it will stabilize the moisture content in the room at this level. If that same coil is running say a 43 degree SST with 55/75 air entering it can spend upwards of 25% of the system capacity condensing moisture from the air. With a regular superheat controlled TXV the suction pressure/temperature can even dip below that point and lead to even more dehumidification of the air. That combined with any heat used to make the steam/moisture has to be removed as well can lead to 2 to 3 times extra refrigeration capacity being needed.
The use of a slightly larger coil to reduce the temperature differential across the evaporator, holding the suction pressure at the dewpoint of the air in the cooler and the downsizing of the humidifier to only provide backup humidification leads to a reduced system cost and a more stable operation.
This can be accomplished by using either fan assisted evaporators or gravity coils. It all depends on the goals of the customer in the room. Many times a reduced airflow fan assisted coil or a gravity coil is desired to reduce the potential for drying out the product.
It is important to size the main line to accommodate the system capacity. To large a line can lead to problems with oil return (burnouts of the compressor will result) or too small can result in excessive pressure drop which will reduce the system capacity. A good utility is the “refrigerant line sizing” program located at boxload.tecumseh.com. Input the parameters of the system and it will recommend a suitable line size for both Liquid and Suction lines.
For a single evaporator the total amount of pressure drop for the suction line should be equal to 1 to 1.5 degree F. This will vary depending on the refrigerant chosen. For R134a the suction pressure drop should be in the 1 – 1.5psig range. For blends (R404a, R407c) the drop should be 1.5 to 2 psig in pressure drop.
When sizing for a multiple evaporator installation break the main line sizing apart from the branches. Each should be sized to add up to the desired total amount of pressure drop for the complete suction line.
For long lineset runs over 50 feet pressure drop and oil return are big issues. Long lineset runs can be done but pressure drop is critical to the system operation. LRC’s lineset charts are based on 100 feet of run. For runs over 100 feet please ratio the pressure drop – for 150 feet the pressure drop would be 150/100 * chart value. Oil return is also a large issue. For long runs over 50 feet or runs with alot of rise where the evaporator is higher than the condensing unit it is a good idea to utilize an oil separator to minimize the amount of oil that leaves the condensing unit. If an oil separator is not used for runs over 30’ then please add 1 ounce of oil for each 10 feet of lineset over 30 feet.
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WE CAN MAKE ALL COPPER COILS!
Did you know copper is a great Antiviral, Antimicrobial, and Antibacterial Metal? As well as anti Corrosive metal which will make it last for years to come!
We are able to make any coil all copper. With copper Tubing, Copper Fins, and Copper Endplates. Viruses and Bacteria cannot live on Copper.
There are many wonderful attributes to copper coils not to mention will help keep Covid-19 off surfaces for long periods of time. Please take a look at this article that will help provide information on what copper coils can do for you!
Due to the Covid-19 Virus and the mandate for all nonessential businesses to close in California, we have decided to shut our doors for the time at our L.A. manufacturing plant. But our Arizona plant is still open!
We are still producing our replacement and OEM coils, as well as our Wine Room evaporators.
You also will still be able to get spare parts to keep your existing units working. We have stock of motors, heaters, fan blades, etc.
Our engineering and sales staff will still be working from home at this time and able to take your calls and Questions.
If you have any questions please contact us at 562-944-1969
THE NEW D.O.E. STANDARDS | Begining of 2020 We will no longer make regular HS, VAH, RM, or VRM models. The EC versions will be the only models available. On the bright side, your customers will be saving tons of money on the energy savings, They will be quieter, and on the HSEC and the VAHEC models, they have filters already installed!
PRICE INCREASE | Due to the ever-increasing tariffs all P.O.’s placed after December 1st will reflect our new prices. For questions please contact our office at 562-944-1969 or email Jonathan at firstname.lastname@example.org. Thank you.
Commercial AC vs Refrigeration – Or Why Can’t I use that Cheaper Mini-Split unit??
Most of the units shown on the internet are commercially available AC units. The standard for the industry is .012 thick copper tubes and most of the systems are not available with a coil coating so you will see coil failures fairly quickly. The LRC designs are based on a thicker copper .016 thick wall and all our wine coils are dipped in a water-based epoxy and cured in the oven. This is done because the wine vapors condense on the coil and get in the interface between the fin collars and the copper tube. The epoxy seals this area so the coils won’t get attacked by the acetic acid.
1. In the case of the mini-split type of system, we do not have an equivalent. We have not been able to find a mini-split evaporator that has a coated coil and can utilize the constant pressure expansion valve.
2. More flexibility. Some systems need cabling between the evap and condenser. The LRC systems are set up to do a pump down the type of system to facilitate installation.
3. Evaporators only. Some resellers sell the entire system. We depend on the wholesalers to provide the condensing unit along with the other system components. We do this because the conditions are different for a refrigeration system between Florida, Phoenix, and Seattle. And only the wholesalers tend to know how to configure a system for their local conditions. In addition, prefer to have the condensing units and other parts sourced locally so in the event of failure parts are more readily available.
MANY TIMES WE GET THE QUESTIONS, “HOW DO YOU SIZE THE CONDENSER WITH YOUR EVAPORATOR?”.
HERE ARE SOME HELPFUL GUIDELINES WHEN SIZING.
- SELECT CONDENSING UNIT WITH A LOWER CAPACITY THAN THE EVAPORATOR ( 90% to 100% OF EVAPORATOR )
- DESIGN POINT – 38° SST (USE 40°F FOR SIZING PURPOSES) IF RUNNING ROOM AT 55°
- GOLDILOCKS TYPE OF CONDITIONS
- USE A GOOD AVERAGE TEMPERATURE NOT WORST CASE SCENARIO
- ON HOT DAYS JUST LET THE SYSTEM RUN A LITTLE LONGER FOR THE OUT OF BOUNDS CONDITIONS
- ROOMS ARE SIZED FOR 16 HOUR RUN DAY
- LOAD ON EVAPORATOR IS CONSTANT- ITS THE CONDENSING UNIT THAT NEEDS TO RUN A LITTLE LONGER
- SIZE TO A REASONABLE AMBIENT TEMPERATURE
- IS IT INSIDE?
- IS IT OUTSIDE?
- SAN DIEGO- SIZE FOR 80° NOT 110°
- PALM SPRINGS- SIZE FOR 100° OR SO AND LET IT RUN LONGER ON THE HOTTEST TIMES OF THE YEAR
- PUT A FAN CYCLING SWITCH ON THE CU TO KEEP THE HEAD PRESSURE UP TO 80° OR BETTER AMBIENT CONDITIONS TO PROTECT DURING LOW AMBIENT TIMES.
- CONDENSING UNIT SHOULD HAVE A SUCTION ACCUMULATOR
SO TO SUM IT ALL UP: SIZE AT A SLIGHTLY LOWER LOAD THAN WHAT THE ROOM IS, AT A PLUS 40° SST, AT A REASONABLE AMBIENT TEMPERATURE.