“Future-Proof” Cooling Systems
Federal regulations in the refrigerant industry are centered on Global Warming Potential (GWP) of past, current, and future refrigerants. Global warming potential (GWP) is a relative measure of how much heat a greenhouse gas traps in the atmosphere. It compares the amount of heat trapped by a certain mass of the gas in question to the amount of heat trapped by a similar mass of carbon dioxide. A GWP is calculated over a specific time interval, usually 100 years. GWP is expressed as a factor of carbon dioxide (whose GWP is standardized to 1). One of the more common refrigerants used for environmental rooms is R-404a (44±2% C2HF5 · 52±1% C2H3F3 ·4±2% C2H2F4). Its primary use is in medium to low temperature applications. However, it is fairly high in GWP at 3,922. Another common refrigerant used in the industry is R-134a (1,1,1,2-Tetrafluoroethane) for high temperature refrigeration. R-134a has a GWP of 1300. Both of these have significantly higher GWP than proposed replacements, but are much more safe and efficient. Two proposed replacements are propane (R-290 with a GWP of 3) and ammonia (R-717 with a GWP of 0). Flammability and exposure with these replacements is different from R-404a and R- 134a and their use will be somewhat slow to be universally adopted. In the meantime, manufacturers of refrigerants are coming out with better refrigerants that have a lower GWP than R-404a and R-134a and better safety than ammonia and propane. HoneyWell and DuPont, the largest refrigerant manufacturers, are introducing replacements such as R-448a. R-448a has a 66% lower GWP than R-404a and similar efficiency with very few safety issues. Commercial refrigeration of the future will certainly change. Given the rapid change of refrigerants and the upcoming regulations, Darwin Chambers may be your best option. All of our R-404a systems are compatible with the new R-448a. Additionally, Darwin Chambers utilizes the PFTCU unit to minimize refrigerant and make quick compressor swap-outs easy whenever possible. Our reach-ins eliminate the compressor entirely when feasible with thermoelectric technology at moderate temperatures.
The Darwin Chambers Precision Fluid Temperature Control Unit (PFTCU) is an indirect cooling system utilizing a combination of refrigeration technologies, glycol/water heat exchange technologies, and the latest temperature control methods to outperform conventional refrigeration systems in environmental chamber applications. Precision Fluid Temperature Control Unit – Benefits
- Refrigeration system is entirely self-contained, no on-site brazing is required, water connections are typically made using cross-linked polyethylene (PEX) or equivalent.
- Refrigeration system is entirely pre-built, pressure tested, vacuumed (lengthy process ensuring micron levels achieved and maintained well below 500 microns), charged (from a digital scale to predetermined levels), energized, and tested in the factory to ensure the system runs properly before shipment.
- System requires a relatively small quantity of refrigerant, no refrigerant is circulated into the environmental room and no refrigerant circulates through piping to and from evaporator.
- Because the PFTCU is pre-charged/tested, there is considerably less time spent installing system, only water (glycol/water) connections are made.
- Because refrigerant is only in the cooling unit, leak testing and repairs are readily performed. If entire replacement is ever needed, the entire cooling system can be replaced (wiring and piping included) in less than 30 minutes.
- Because propylene glycol is continuously circulated through the room, a large, rapid temperature rise is avoided during failure of cooling unit.
- Redundant cooling systems need only be placed in-line with one another, with nothing but the addition of a small amount of piping and ball valves for disconnection. Failure of one system will not contaminate or compromise the piping of the other system or the room evaporator/air handler.
- Small leaks in the evaporator/air handler will take an exceptional amount of time to cause a temperature rise. The propylene/glycol mixture does not escape through microscopic holes nearly as fast (months instead of minutes) as refrigerant gas.
- Pressure on piping is drastically less than compared to refrigeration piping, 1 or 2 psi compared to up to 100+ psi with refrigerant gas. In rare instances of leaks in the room evaporator/air handler, the fluid level can simply be topped off and the system can be serviced weeks, months, or years later – at the customer’s convenience.
- Entire cooling system can be installed and replaced, quickly, with simple tools – no refrigeration tools or certified technicians necessary.
- Because the PFTCU can operate in two modes, cooling/heating with refrigeration and cooling/heating with continuously circulating fluid, this system is more efficient and inexpensive to operate. As one should expect, a large refrigeration system should not be required to maintain temperatures near or above 40°C. With the PFTCU, the compressor is de-energized when the desired temperature goes to higher levels and only the ultra-efficient (and reliable) circulator pump is used to cool the room. No other manufacturer has this capability.
- Service costs are reduced, sound levels are minimized, energy expense is reduced, and temperature control/uniformity is un-matched.
Humidified chambers typically have a pan of water that is heated with electricity or an element sprayed with water creating steam. This leads to heat being introduced into the chamber as well as imprecise addition of humidity. Mineral scale build-up is also quick. In conditions with dew-points close to the actual temperature, this creates supersaturated localized conditions and leads to condensation in the chamber at conditions where there should be none (for example 40°C and 75% RH). Our systems add humidity through an ultrasonic vapor generator. We can turn it off and on in mere seconds. It doesn’t generate any heat. It doesn’t overshoot or continue to add humidity past the set point. It doesn’t collect mineral scale. However, they do require replacement of inexpensive titanium ceramic discs every 10,000 hours of use – which most users do themselves. We also suggest the hook-up of deionized/distilled water or use of reverse osmosis units (we sell these). Otherwise, mineral scale build-up will occur in the chamber.
Why Ultrasonic Humidification is important:
- Saves 93% on operating costs at 25°C
- Has less heat output- room air conditioning loads are reduced
- Is more reliable and operation can be checked visually
- Diminishes localized hot and cold areas within the chamber leading to less condensation issues
- Is maintained or repaired easily by operators even with limited skills
- Runs at almost no noise level
- Reduces maintenance and costs
Darwin Chambers Company utilizes antimicrobial handles on our walk in chamber doors. Our exclusive technology antimicrobial coated handle helps stop the spread of illness-causing bacteria and fungi. More ammunition is the continuing battle against bacterial menaces in your research, even E. coli, staph, and salmonella. Our antimicrobial coating works to suppress growth of a wide variety of bacteria, algae, mold and mildew for the life of the hardware. When it comes to passing along germs, hands are the winners. No matter how many times a day they are washed, hands are bound to pick up pathogens as they go through their daily routine. Every time someone opens a refrigerator, oven or cabinet, potentially harmful microbes may find a home on the handle to the chamber. The next person using the contaminated handle unknowingly passes on the pathogens to whatever they touch. Darwin Chambers antimicrobial handles offer powerful bacteria-fighting action that should last the lifetime of the chamber handle. The more the handle is used, the harder the antimicrobial coating works to retard the growth of illness-causing pathogens. No special care is needed, handle normally and use standard cleaning methods.
How antimicrobial coatings add value:
- Reduces the spread of pathogens – even E. coli, staph, and salmonella.
- Provides antimicrobial protection for the life of the handle.
- Retains efficacy with normal use and cleaning.
The silver-ion based antimicrobial compounds are:
- EPA registered
- FDA compliant
- NSF listed