Temperature mapping is a procedure that forms a dynamic, thermally-active picture of what’s taking place within a cooling unit. Generally speaking, we accomplish this process by placing special monitoring devices throughout the cooling enclosure. Then, as the data is collated, a mapped thermal image is produced, one that illustrates the location of any warm spots. Remedial action is the next step. Before that, though, we need our monitoring devices.
Installing Data Logging Monitors
Electronic monitors are first on our agenda. These devices measure localized temperature variances while creating a time-based log. Hours and days of data are recorded, with the temperature spikes and dips generating a real-time graph of the overall conditions inside the freezer. The temperature probes are handy, in an of themselves, but their true purpose only comes to light when their results are combined.
Spikes in the temperature axis begin to make sense as we pair results with the time the event took place. A door, for example, may have been left open during the midnight shift, but the incautious practice hasn’t escaped the attention of the time mapping apparatus. Let’s put the time domain to the side for a moment, though, while we consider the spatial aspects. Remember, there’s a group of strategically positioned temperature probes in use here, and they’re all adding their input to the map. If a particularly nasty spike is generated on one of these monitors, well, the location of that unit needs to be checked out on the coolroom map. In this case, it’s likely that an insulating panel is faulty and energy losses are taking place.
Decoding the Coolroom Image
The various drops and ramps on the temperature mapping scale look like an inky sprawl to the casual observer, but an expert refrigeration engineer sees the whole picture as he studies the progressing line. Convection currents are possibly being hampered by a wall of poorly arranged storage materials for example. Fortunately, corrective action strikes swiftly when the problem is located. In this example, full cooling distribution is restored when the airflow problem is fixed.
Regular temperature probes are handy, certainly, but their output only provides a limited thermal profile. Electronic data logging monitors (EDLMs), on the other hand, collate the thermal data and add a time axis to the plotted graph. Finally, a spatial element ties into the recording procedure as the intelligently located probes provide positional information, data that flows from every nook and cranny within the insulated storage unit.
Contemporary coolrooms are fully enclosed chambers. There’s real thermal seclusion here, except for that one conduit connecting the isolated enclosure to the outside. This is the air inlet channel, a conduit that reaches outside the system. Not to worry, there are filters in place to stop airborne contaminants in their dirty tracks. But what about the temperature of that air? Just how do external temperature factors affect coolrooms and freezers?
It’s the Little Details
In planning for the bigger issues, we can miss the smaller problems. A door seal is repaired, for instance, but the damaged door clasp goes unnoticed. Freezers and coolrooms won’t discriminate between a tiny error and a gaping problem, not when they can use both issues to cause significant energy leaks. Likewise, the outside environment is anything but a constant. It climbs in the summer and drops precipitously in the winter to produce a system-fatiguing variance factor.
Determining the External Thermal Envelope
A temperature differential exists in the inlet channel. The energy, the warm or hot air pulled into the vent, is being told by a thermostat to cool way down, perhaps below 0°C. The laws of energy conservation are happy enough to accommodate this thermostatic requirement, but heat can only be removed from the air as fast as the refrigeration system allows. That’s where the evaporator and condenser coils enter the cooling formula, for these parts will absorb the heat, but they can only do so as fast as their mechanical innards and the refrigeration medium allows.
Assessing Outer Temperature Loads
There are differential equations and thermal dynamics formulas that lend this theory concrete shape, but we don’t require the aid of intricate mathematical theorems, not when we’re just trying to add context to a relatively simple processing environment. Suffice to say, it takes great quantities of refrigerating energy to offset that temperature differential. If the required thermal setting is approximately 0°C, then a 37°C day will impact the system. That impact grows when lower temperatures are desired, such as those found in a freezer, for a much larger differential exists between the hottest summer afternoon and the coldest arctic environment.
Capable coolrooms and freezers address internal thermal factors. The finest systems take that operational principle a step further. They maintain that chilled air level, no matter how hot (or cold) the weather becomes outside the refrigeration envelope. This outer thermal envelope is beyond the system’s control, but the refrigeration unit will quickly accommodate the differential, thus maintaining a uniform temperature coefficient that offsets the prejudicing influence of the outdoor air.
C&M Coolrooms can create a custom solution for your specific needs. Talk to one of team members today.