New Energy Efficient Refrigeration System Design with precise De-Greening Control and Hot Water Recovery for Naranja Packers PTY(Ltd)

A unique partnership to improve the cold chain and de-greening of soft citrus for designated international markets from our own Mpumalanga province, South Africa, is bearing fruit. The partnership between Naranja Packers, Pienaar’s Refrigeration and Metraclark brought about the development of trusted refrigeration technology and systems that are not only more energy efficient compared to previous generation refrigeration equipment, but also offer free water and air heating as well as precise temperature, humidity and de-greening control.  


‘The new facility upgrade is part of the expansion of our packing facilities at Naranja Packers near Burgersfort to ensure the group keep up with the increased market demand. It is a two part process which includes the de-greening element where soft citrus fruits are treated to ensure a perfect fruit colour, as well as the enlargement of our dispatch facilities to accommodate the final product,’ says Thinus Boshoff, Maintenance Manager at Naranja Packers.


The “De-greening” process for Naranja Packers is designed to “de-green” early season or green citrus fruit to meet customer and market demands. These rooms are specifically designed for precise clean air, humidity, temperature and ethylene control. Ripening of fruits is a perfectly natural and highly desirable phenomenon leading to increased sweetness, flavour development and softening of the edible tissue. 

Among the requirements was a Cold Chain that was as energy efficient as possible in light of the energy crisis in South Africa,’ says Nicolaas du Plessis, Metraclark Application Engineer.


To ensure all client criteria stipulated for both the de-greening and the dispatch rooms are met, an in depth heat load and equipment design was done in conjunction with the client, the contractor and by the Metraclark Engineering Department. 


Du Plessis says there were a number of benefits in using this specific design.


‘The heart of the refrigeration system consists of the latest Copeland Stream compressor technology, offering the highest efficiency in this capacity range. For capacity modulation to meet application demands, Variable Speed Drives and Alco Electronic Expansion Valves were fitted, thus ensuring precise capacity control and enhancing the system efficiency even further. The Variable Speed Drives also reduces the start-up current spike, caused by the in-rush current of a locked rotor starting compressor, by slowly speeding up the compressor’ he says.


Brazed Plate Heat Exchangers were installed between the compressor and the condenser on the Discharge line. The heat exchanger is used as a de-superheater. The term de-superheater states that the heat exchanger is absorbing heat from the discharge line, adding the heat to the water that flows through the heat exchanger. The heated water is then supplied to the steam pots, which are used to control the Relative Humidity Percentage in the room, thus reducing the power needed to heat up the water inside the pots.

The design team also looked at how Naranja Packers can more effectively monitor the various de-greening processes. Dixell IPro Control systems was selected to monitor all the relevant criterion in the de-greening room, by doing this it adapts the relevant equipment to ensure that everything stays within the boundaries of operation.


‘Dixell EVO Monitoring Systems was installed to monitor and store the cold chain temperatures 24 hours a day, according to HACCP standards. This enables the client to receive, control, store data and compile different reports at a central point from all the electronic controllers connected in the cold chain. This data can be retrieved at any given day during its operation, assisting the installation and maintenance contractor to look at the system history and set up systems for optimum running conditions. The client, in this case Naranja Packers, can also analyse historic temperatures and adjust accordingly, to best suit their requirements. The saved data will also enable Naranja Packers to professionally communicate real time information with their clients at all times. The Dixell EVO also serves as an alarm unit with the capability of sending e-mails or sms real time information to the relevant parties involved,’ du Plessis explains.


Naranja Packers is one of the major citrus producers in South Africa and the overhaul of its facilities has increased its capacity to export fruit to overseas destinations.


‘The de-greening facility has the capacity to handle 840 bins or 306 tonnes of citrus at one particular time and we usually remove a batch every three days and replace it with a new contingent. Our dispatch cooling facilities can accommodate about 700 bins or 255 tonnes,’ says Boshoff.


The first phase of the project kicked off at the end of 2015 and the final phase will be completed in early 2017.