Success story on the project of the first forced pre-cold of hass avocado in Colombia.
By Daniel Puerta*
Westfalia Fruit inaugurated last Friday, January 18 in Sonsón, Antioquia (Colombia) one of the most modern hass avocado packing in Latin America.
From these beautiful lands of eastern Antioquia, Westfalia Fruit hopes to continue the growth in the North American and European markets of this precious fruit. For this task, the new baler has a state-of-the-art fruit sorting machine from the New Zealand brand Compac; which is capable of processing up to 16 tons per hour.
However; to meet high import standards, the fruit must be in a temperature range of 5 to 6 degrees Celsius, so Westfalia Fruit turned to the design services of MB Engineering, a company specializing in industrial cold chain design, for its refrigeration system consisting of an entrance antechamber, 4 rooms with capacity to cool and store 250 tons of fruit in 24 hours, two dispatch docks and a forced pre-cold.
This forced pre-cold for hass avocado stands out for being the first in Colombia and one of the few existing in Latin America (There are only some in Peru and Chile). This system is capable of cooling the fruit from 19 to 6 degrees Celsius in just 5 hours, with a capacity of 10 pallets; equivalent to 12 tons, reducing by 58% the time needed for Westfalia Fruit to have a complete container ready to be shipped.
To achieve these figures, the forced pre-cold has a reversible flow evaporator, from the German brand Thermofin, which has 4 powerful fans of 4 HP each, with the ability to overcome the pressure drop between the pallet boxes, and which maintains a constant speed of 2m / s on the product; so it allows an even cooling without drying the fruit.
With the help of the Colombian company Sutrak; In charge of the installation of the cooling system, the pre-cold has a switched logic programmer (PLC) for the control, which receives the signal from 6 sensors that record both the internal temperature of the fruit, as well as the temperature of discharge and suction of the air. The key to the proper functioning of the forced pre-cold avocado is the distribution of the sensors, where two are located on the outside and two on the inside of the pallets, both at opposite ends.
The system initially works for 3 hours, during which the external temperature of the pallets is expected to reach 7 degrees Celsius. If this does not occur in this time span, the system continues to operate for 30 more minutes, to ensure that the set parameters are obtained. After reaching the desired temperature on the external pallets, the fans stop completely and begin to rotate in the opposite direction for the remaining time of the cycle: Between 1 hour and a half and 2 hours, to obtain a high degree of uniformity in the temperature of the hass avocado, with temperature differential of only 0.5 degrees and an average final temperature in the center of the fruit of 6 degrees cent igrades.
The function of the ambient temperature sensors for discharge and suction of the air is to prevent the temperature in the chamber from being below 1 degree Celsius, as this could dry and damage the fruit, and would not be detected until the moment of being consumed, therefore MB Ingeniería specified the need to carefully control the air temperature, generating an alarm if the ambient temperature of the room decreases below what is desired. In addition, the system has an electronic expansion valve, which allows to control all the time the overheating of the evaporator, avoids the decompensation of the system by the variation of the load throughout the cycle, in order to obtain the maximum efficiency of the evaporator at all times, at the same time that an energy saving of 15% is generated and the service life of the compressor and the system in general is extended.
To achieve maximum efficiency of the system, MB Ingeniería specified a retractable tent to direct the flow of air, so that it is forced to pass through the openings of the boxes and no losses or short circuits are generated in the system; in turn, in the company of the company in charge of the installation of the tent, Andertec, a system of barriers was designed so that the air cannot circulate through the wooden stowage. This system adapts to the different types that Westfalia Fruit handles for different destinations, varying between pallets for boxes of 4 or 10 kilograms.
With this design of forced pre-cold for hass avocado, MB Ingeniería managed to generate a practical and efficient solution for the need of Westfalia Fruit to adapt to the current times of the market that do not wait. In turn, he provided constant technical support, uniting different companies with their respective products and disciplines to make this project a reality today.
Thanks to the excellent results of the system, Westfalia Fruit already has in its sights the next step in its modernization: the installation of two additional forced pre-colds to reduce by 80% the time needed to have a complete container ready to be shipped, and with the help of MB Ingeniería this new objective will soon become a reality.
Note: Colombia exports hass avocado to more than 20 countries in the world, spread across North America, Europe and Western Asia.
Note: Colombia is positioned as the fourth country in hass avocado production, but expects to reach the first position in 2020.
* Daniel Puerta is an engineer at MB Ingeniería. [email protected]
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