OPTIMISATION OF COLD ROOM STORE WITH HOT GAS DEFROST
SUCCESS STORY – AKOCORE ADVANCE
AKOCORE ADVANCE, by means of its Self-Drive (c) algorithm, and its robust mechanism, capable of controlling loads of up to 2CV through its five relays, acts on all the loads in the cold room store (compressor, fans, defrost, drainage resistor etc.), optimising electricity consumption, product conservation and extending the operating life of the facility.
AKOCORE Advance (AKO-16525A), is a controller for cold room stores developed by AKO. It includes the SELF-DRIVE© algorithm, which autonomously manages the cold room store, adapting at all times to how it is used and its environmental conditions. It has the following benefits:
Fast, simple and error-free installation:
• It only needs two NTC probes (ambient and evaporation), which makes it quick, simple and also economical.
• You only need to adjust two settings, thereby avoiding programming errors and later fine-tuning of settings.
• It has 5 2CV power relays to handle all cold room store loads; it is not necessary to mount an additional power contactor box.
Improves Product Conservation:
• Considerably increases the Set-point range time, leading to better conservation of the stored product.
Lower Maintenance Costs:
• It stops ice from forming in the evaporator—one of the most common reasons for system stoppages, which leads to further costs and necessary steps.
• It means the compressor has to be activated less often, does not have to kept running for so long, and extends the working life of what is the most expensive part of the system, plus it reduces mechanical stress, which is one of the main causes for gas leaks.
• It reduces the number and lengths of defrosts, reducing thermal stress on the evaporator, and therefore the risk of gas leaks.
Evaporator lock and Evaporator controlled by AKOCORE Advance.
Reduces Energy Consumption:
• Energy consumption in the cold room store can be brought down considerably by reducing compressor and defrost times, and by preventing sudden temperature changes due to defrosting.
• It has an Open Door alarm to encourage responsible use of the cold store room.
ORIGINAL REGULATION OF THE COLD ROOM STORE
The Cold Room Store has the following characteristics:
• Condenser unit power: 5,025KW III
-Fan power: 150W
-Hot Gas Defrost
The cold room store consists of two cold circuits, two condensing units each of which feeds an evaporator with a single fan. There is a lot of movement in a cold room store, plus it has a high product load.
The two solenoids operate simultaneously and defrosting was carried out by means of two mechanical clocks which were programmed at alternate hours.
Measurements were initially taken of the pattern of the cold room store controlled by the existing controller (Electronic Thermostat 1 relay + Defrost clocks)
This was measured by connecting the AKOCORE ADVANCE AKO-16525A controller probes, connecting a door switch to the digital input and recording the data in the CAMM Module. These values are taken as a reference for the comparison described in this document.
Data Collected on Existing Controller:
As displayed in the above table, setpoint time was only 66.8%.
This was mainly because as defrosting is controlled at alternate hours, the heat contribution in the cold room store was very high. The cold room store was also used 24 hours a day, so there was a lot of staff movement. 30% of the heat contribution to a cold room store is estimated to come from opening of the door.
The system did not give a warning if the door was kept open for too long, plus the fans didn’t stop working when the door was open, so that employees sometimes didn’t know how long it had been open. And staff found it quite uncomfortable working in the cold room store due to the continuous ventilation.
REGULATION WITH AKOCORE ADVANCE
Once the performance measurements had been taken with the existing controller, all the relays of the AKOCORE ADVANCE controller were wired so that controlled the cold room store and the two refrigeration circuits:
• The COOL relay was connected to the two solenoids of the cold room store to work in parallel the same settings as before.
• DEF relay was connected to the reverse cycle of Condensing Unit 1, to activate the Hot Gas defrost. The AUX1 relay was connected to the reverse cycle of Condensing Unit 2, to activate the Hot Gas defrost
• 3 probes were connected, one ambient, and one in each evaporator to detect when defrosting was over and to be able to stop it independently, also leading to much more efficient regulation. These two probes also continuously measure the state of the gas in the evaporator and the Delta-T compared with the ambient probe.
• The FAN relay was connected to the two fans simultaneously, and the settings were adjusted so that they stop when the door is opened.
• The open door alarm was activated, by connecting the door limit switch signal to digital input 1 of the controller
• We started up the equipment with the two parameters described above (type of installation and setpoint)
From this point on, the AKOCORE ADVANCE controller started to regulate in standard mode (i.e., like any parametric controller, performing defrosts programmed by time), while performing the initial calibration.
The controller calibrates when it is switched on, and it takes 4 or 5 hours, so the controller knows the status and use of the cold room store.
When this calibration is finished, the controller automatically activates the Self-Drive mode (c), and begins to optimize the camera regulation, obtaining important advantages, as explained above.
Importantly, if the controller registers any data it does not understand (one of the probes is incorrectly positioned, has fallen, etc.), it automatically switches to Standard mode, and gives a warning to solve the incident. In other words, the cold room never stops controlling refrigeration if incidents occur.
RESULTS AND COMPARISON
After taking the data collected by the CAMM Module the following improvements were achieved:
-31% Electricity consumption
-80% Defrost time
+31% Time in set-point
-6.339 Kwh per year
<5 months return on investment