Interview - Creating Efficient Refrigeration Systems

Data availability is crucial to make informed decisions. But depending on the industry, some data is especially important to have. What kind of data is essential for businesses in the cold chain to make the best decisions?  

There are three key areas relating to data within the cold chain. The first is legislative temperature monitoring, ensuring that products are stored at the correct temperatures throughout the cold chain process. Businesses can gather temperature data using a range of product probes and temperature-calculating algorithms. Storing all data centrally in a control and monitoring system front-end allows all data to be accessible when needed for compliance purposes. 

The second is asset maintenance. It is essential to maintain all HVAC and refrigeration assets to ensure trading availability and eliminate stock loss which are key to any business. Traditional alarms generated by faulty equipment or surpassed thresholds encourage reactive maintenance after a breakdown has occurred. Several data sources assist proactive and preventative maintenance to catch issues early before severe faults disrupt trading or cause costly repairs. Software is available to provide the necessary data that highlights problem assets which allows users to act on developing problems before failures reach critical points. Site performance analysis software can be used to identify problem sites.

The third is energy monitoring. Key equipment can be electrically sub-metered and can then be monitored at enterprise level. Specific areas such as suction pressure or whether night blinds were deployed can also be monitored. Our new Refrigeration Performance Indicator (RPI) feature can measure cabinet and cold room evaporator performance, along with electrical energy input and heat reclaim energy output generating an overall system Coefficient of Performance (COP). Not only can this feature guide the selection of equipment and system designs, but it is also a useful tool in highlighting problem assets and driving proactive maintenance.

What part of a refrigeration system might run inefficiently without businesses being aware of it? 

If only standard temperature or equipment failure alarms are utilised, various equipment can run inefficiently without businesses being aware of it. For example, cabinets can run colder than needed if settings are not correctly reviewed. Refrigeration plant might run lower pressures than needed. Blocked condensers can cause fans to run more than necessary whilst not reaching critical alarm levels. Also, external environmental impacts such as ventilation ducts blowing into open cabinets can cause increases in refrigeration energy use whilst the cabinet is still maintaining temperature and not generating alarms. When cabinet night blinds are not being used it can generate significant and unnecessary energy consumption, whilst again the cabinet will not generate over-temperature alarms.

What could be set up inefficiently?

Equipment should always be configured to the manufacturer’s recommended settings. However, often these also require some fine-tuning to suit individual sites and systems. There should be an acceptable range of settings stated by manufacturers against specific settings to allow this site-specific commissioning. Following commissioning, it’s important to control settings to ensure these do not deviate resulting in poor performance or inefficiencies. This could include general cabinet or coldroom settings and refrigeration plant settings, but can also include such things as electric defrost timing and cabinet lighting timing that can impact energy costs. Some system sensors also need to be correctly commissioned to ensure both performance and efficiency such as pressure transducers having the correct offsets set. 

Another area that may be affected by incorrect operations is site-level control initiatives. Specific equipment may be configured to switch set points at specific times such as peak energy periods or overnight. These set points and timings could be incorrect, either to suit site operations or to maximise energy savings. PLC software can be utilised to implement control-based energy initiatives and monitoring strategies can provide visibility, management and control of these operations.

How can businesses assess if they chose the right equipment?

With such emphasis on energy consumption presently there are many varying equipment, plant and system designs being tried and tested. It can be difficult to assess which equipment or system designs offer good performance and energy efficiency. This can result in not achieving the full efficiency potential and can impact significant numbers of sites when equipment or systems become specified or are rolled out across an estate. 

There can then also be site or system design elements that can impact both performance and efficiency such as undersized or oversized condensers, condenser location or system design criteria. Other non-refrigeration system site design elements such as airflows from external doors or ventilation systems can also impact on open display cabinet performance and efficiency. 

Another area, often difficult to assess is energy-saving initiatives such as retrofitting energy-saving equipment to existing assets or recommissioning settings. Without the correct analysis, significant costs can be incurred without gaining the expected efficiency savings, or system performance can be impacted. It has always been recommended that any initiatives should be fully monitored to capture all relevant data points to allow analysis of both energy and system performance.

Should any initiative be impacted by external factors such as ambient, trading hours or other system operations, then regression analysis is vital to normalise results. Since RPI now offers the ability to provide individual asset energy reports along with overall system performance, RPI significantly improves assessment and also allows conversion from refrigeration energy use to the financial impact on the business. This helps businesses to select the correct equipment or initiatives.

Some businesses have data available but are unsure how to use it to make changes. For those who are overwhelmed with data, what might be a good starting point to develop a new energy-efficient strategy and put action in place? 

Get the settings right first

Utilising recommended settings along with site-specific fine tuning, ensures things are set to maximise both performance and efficiency. Then it's important to ensure the system is locked down to prevent ongoing unwanted changes. 

Ensure equipment is operating correctly

Equipment and systems must be maintained correctly to ensure both system performance and efficiency, and also to allow the correct settings to work. Often settings are tweaked to overcome failures resulting in poor performance or efficiency.

Ensure the right people can see the right data

Whether it is site staff, maintenance contractors or client management, it is important that people have easy access to the relevant data and only the relevant data. On site, this can be achieved by hiding unwanted items, setting up discipline-specific assets or items and setting up data exports for specifically required data. At enterprise level, automated scheduled email reports of specific data sent to the relevant people can support analysis. 

Analyse the data

Businesses can use all the relevant data to identify good and inefficient performing equipment. Available data includes alarms, temperatures, pressures, refrigeration performance, system COP, valve performance, optimisation performance, asset availability, night blind warnings, and energy consumption data.

Target specific inefficient equipment

It is likely that there are limited resources to allow acting on all possible areas. Picking a specific metric to target, gathering the relevant data, and rectifying the issues of the worst performers first helps businesses to make consistent, impactful changes.

Learn from good performers

As well as targeting inefficient sites or equipment it is also important to assess good performers. This information can be utilised to select and specify the best equipment, system design, and settings.

Specify, roll out, and control

Considering the above actions, it is vital that controlled processes are in place to assess, specify, and roll out equipment, commissioning, or initiatives to ensure improvements are realised and importantly that the benefits continue to be realised. Therefore, systems, settings and operations must be locked down, monitored, maintained, and controlled on an ongoing basis.