Kaiaponi Farms

Kaiaponi Farm began their story in 1907 when the land was used for cropping. The land has since been used to grow many fruits and vegetables including apricots, avocados, beans, grapes, pears, squash and tomatoes. Today Kaiaponi is a leading grower of apples, kiwifruit and feijoas.

Kaiaponi is a privately-owned business based on family values and the importance of innovation and sustainable growth has always been central to the Kaiaponi ethos. This has been demonstrated in the past by their early investment in gold kiwifruit, high yielding apple varieties, designated grower trial blocks and a continual investment in post-harvest technology.

They have also led the market in implementing sustainable cooling technology, recognising the need for high-quality solutions that provide the best climate-controlled environments to deliver quality product and high crop to table yields; while minimising impacts on the environment.

The success of the business has meant an ongoing program of investment in cooling capacity and General Manager Scott Wilson has had to consider the growing impact of legislation aimed at changing use of F Gas refrigerants while looking for technology that could offer future proofing and competitive advantage.

The Challenge

With typical refrigeration systems large temperature differences between the refrigerant evaporating temperature and the air temperature can exist, leading to substantial dehumidification of the air. This dries out product and causes product weight loss.
To prevent this the challenge was to design a plant that would not only operate efficiently at high load, but also under low load conditions, while maintaining optimum room temperature and humidity.

Kaiaponi wanted a refrigeration system that would have:

• Very low temperature difference between the cooling units in each coolstore and air temperature, with optimum humidity to keep water in the product and reduce or even eliminate, the need for defrosts.
• Compressors that were always operating at an efficient level with the ability to adjust to the refrigeration load.
• Efficient methods to reject heat from the system.
• Energy efficient refrigerant that was cost effective and future proof against raising costs and risk of supply high global warming potential (GWP) refrigerants are now subject to.
• Modern control systems that allowed monitoring of all parameters and provided a history of system performance.

Solution

Providing design and installation of new coolstore facilities, EcoChill also provided engineered plant to meet Kaiaponi specifications for a primary and secondary refrigeration system.

EcoChill Primary System

The EcoChill cooling plant is contained in an external weather proof enclosure housing the entire primary refrigeration circuit. It consists of the compressors, condenser, expansion valves and evaporator.

• The physical circuit is short, meaning the refrigerant charge is very low. A typical EcoChill installation will use around 10% of the refrigerant in conventional systems.
• No refrigerant leaves the cooling plant which means there are no long copper pipe runs; drastically reducing ongoing maintenance and the risk of leaks.
• As the refrigerant does not enter the coolroom, more efficient natural refrigerants can be used. The EcoChill cooling plant is designed for hydrocarbon refrigerants to mitigate compliance issues.
• Evaporation of the refrigerant occurs in the cooling plant heat exchanger and is electronically controlled by a highly accurate electronic expansion valve (EEV). This leads to the plant operating at an optimal balanced load. On a conventional system the evaporation is controlled by mechanical TX valves on every single evaporator in the room – they are not as responsive to a changing load and cannot easily be adjusted.

EcoChill Secondary System

The EcoChill cooling plant evaporator is a heat exchanger that cools a water and glycol solution which is pumped into the coolrooms. This secondary system design has a number of benefits:

• The glycol can be kept closer to the target product temperature, resulting in a low temperature differential. Conventional evaporators work at -6 to -7°C which excessively chills the air and causes water vapour to freeze on the coils. With an  EcoChill system the glycol is running at -0 to -3° which means the humidity in the room is not being reduced and there is lower risk of freezing the product.
• Simple coolroom installation – cold glycol is pumped around the room through the room heat exchangers. There is less maintenance due to the elimination of expansion valves and defrost elements.
• If damage ever occurs to the equipment in the coolrooms, no refrigerant is lost – all the refrigerant is in the EcoChill cooling plant. The coolroom only contains water and food grade glycol.

Zero Defrost

The EcoChill system does not have the problem of conventional refrigeration – frost build up on the coils requiring the installation of electric defrost elements. Room humidity is higher because large amounts of moisture are not being lost down the condensate drain during each defrost cycle.

Results

Kaiaponi found the EcoChill engineered solution provided a wide range of advantages over pre-existing technology:

Defrosts

• No defrost is required for rooms operating at or above zero, reducing additional heat being introduced to the room and negating the large temperature rise associated with traditional defrost cycles.
• Defrost for rooms operating below zero, with an on demand defrost system rather than the traditional time based approach radically reducing the number of defrosts required.

Variable Humidity Control

• Temperature and humidity stay constant under normal operation, something conventional systems cannot do.
• Humidity in the coolroom can be consistently held at specifically controlled levels.
• Product quality maintained and dehydration and shrivel prevented, as moisture is not being drawn out of the product.
• By keeping the moisture in the product the system supports higher weight and better quality product when it comes times to sell.

Energy and Operational Saving’s, Low Carbon Footprint

• Natural refrigerants have proven to be more efficient than their synthetic counterparts.
• Use of smart electronic controls and variable speed drives provide a more balanced system with lower power consumption.
• Environmental impact targets are supported through the use of natural refrigerants that are not ozone depleting and have virtually no global warming potential (GWP 0.0009 times that of R404a, 0.0016 times that of R407F and 0.0024 that of R134a).
• Lower on-going costs due to the increasing impact of carbon pricing making the cost of traditionally used synthetic refrigerants increase.
• EcoChill systems have a minimal refrigerant charge compared to a conventional system that would have used as much as 10 times more refrigerant, meaning lower service and maintenance cost and decreased risk.
• Having a central system enables simple cost effective heat reclaim for hot water production when required.

Intelligent Technology

•  Intelligent control systems maintain optimum operating conditions.
• Systems have remote access, control and reporting.
• Data logging of temperature and humidity verify the EcoChill system is performing optimally and support wider company reporting requirements.