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Food logistics – too much energy bills? Future trends that need to be implemented today

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As I mentioned in previous columns, the very fact of moving away from F-gases and switching to CO2 is a technological revolution. A revolution that allows you to save from 20 to over 50% of the electricity used by refrigeration. However, this is not the end. The drastic change in the entire market resulting from COVID restrictions, abrupt increases in electricity and gas costs, and less and less qualified refrigeration technicians mean that technologies that used to be just theory, tomorrow … today must appear in specific implementations.

  • Following the trail of energy savings, cogeneration, or more precisely polygeneration, should be mentioned first. This technology consists in the production of own electricity by cogeneration modules, most often powered by gas. As waste, there is heat from cooling the engine block and exhaust gases. This waste should be directed to an absorption chiller (MAYA), which, properly connected to the refrigeration system, will support it, increasing energy efficiency to previously unprecedented values. We have already designed such facilities and they are under construction. The average yearly COP of the refrigeration system (MT and LT) will be close to 5!

  • Further in the topic of energy savings -> Defrosting and heating the floor with hot glycol. As a general guideline, MT coolers have defrost heaters with electrical power equal to 25% of cooling power and LT coolers equal to 100% cooling power. These heaters (usually) work four times a day for about 30 minutes. For the previously considered system MT = 1000 kW and LT = 200 kW, this gives a daily energy consumption of 900 kWh and an annual cost of PLN 300,000 for defrost alone! Replacing electric defrost with glycol therefore has two advantages; drastic reduction in energy consumption and much greater efficiency.

  • Intelligent control systems such as those provided by DIGITEL. The first and basic task of such a system is to regulate all elements of the refrigeration system. The artificial intelligence functions will “learn” the operation of your refrigeration system over time and when it deviates from the optimum (fault, frosting, etc.) it will automatically inform the staff. This will prevent prolonged fault operation or excessive power consumption. A modern control system should also automatically communicate with the staff via a phone or e-mail application. A more intelligent and better connected control system will reduce the number of service interventions requiring the arrival of the service.

  • Large installations have the potential to produce heat. As a general rule, the amount of heat is 25% greater than the instantaneous need for cooling. This means that each megawatt of cooling capacity can heat 250 single-family homes. For a 1000 kW system operating continuously, the value of heat recovery is PLN 2.6 million per year! However, you should be aware that refrigeration systems for logistics do not work at full load all year round. I am waiting for an implementation in which the refrigeration system operator will sell heat to the municipal network. We can calculate the profitability of such solutions very precisely.
  • There is also a trend of the future – non-technical, and it consists in implementing a company organization that allows the use of new technologies. The cycle of events that leads to the successful implementation of modern refrigeration and large energy savings is not so much long or difficult as it is different from the purchasing processes implemented so far. Many of the technologies described above are new and thus, the Customer may not know about them. The installer may not know about them. Technically, they are uncomplicated, but they require a slightly different approach to estimating the cost of life of an object. I mentioned the consequences of careless implementation of innovations in an earlier column. As a purchasing specialist who is particularly sensitive to energy savings, I can recommend Artur Fydryszek, who also runs the blog www.profelsjonalnezakupy.pl. Our column on buying economical refrigeration will be published there soon.

As a consultant, I participate in projects in which the above-mentioned technologies are already commercially implemented.
So the question arises whether we are really talking about technologies of the future.

Food logistics – too much energy bills? Optimization of F-gas systems

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It is natural that in the case of the construction of a new facility, the Investor, the Client and the designer are working on an open card that can be filled in with any refrigeration installation.

Most refrigeration installations, however, are not new and were created at a time when r744 refrigeration was not available. In the case of facilities with a capacity below 1MW (MT), as a designer and auditor, I often come across systems based on F-gases (popular r404a, r448a, etc.). This technology today is far from optimal, but this does not mean that it cannot be optimised.

Below are graphs of energy consumption of the installation we have recently audited.

The audited installation has a cooling capacity of MT 750 kW and a freezing capacity of LT: 130 kW and operates on r448a. As for a logistics facility, the cold demand profile is very flat – close to that of supermarkets. The facility is used very intensively and the main source of energy to be removed is too warm goods from the delivery and exploited docks both at the receipt and delivery of goods.

We had no influence on the method of operation and the temperature of the goods, so we focused on the operating parameters of the installation.

As a result of measurements over time, it turned out that they can be significantly improved without compromising storage temperatures. As a result of our actions, the energy consumption of the installation decreased by 20.8%! Which will save this client PLN 511,000 per year. We recommended further optimization activities that can bring an additional 5.5% and PLN 130,000 in savings per year. However, they require careful programming/time adjustment.

Unfortunately, due to the retrofit in the installation with too small condensers, further optimization will not be possible.

As can be seen from the above example, the potential for large energy savings is not only associated with the construction of a new installation. Since 2008, I have carried out hundreds of audits of existing refrigeration installations and most of them have a savings potential of between 8 and 16%.

Food logistics – too much energy bills? Designing new facilities – what technology is optimal?

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In previous columns, I wrote about the general principles of designing refrigeration installations in logistics centers and about the optimization potential of existing F-gas installations.

As a refrigeration engineer, I am fortunate to work during the greatest technological change in refrigeration since the end of World War II. One by one, industries are saying goodbye to “freons” and replacing them with r744 refrigeration (CO2 – carbon dioxide). At the outset, it should be noted that it is not possible to convert an old installation into a new one for CO2. So we are talking about setting up a new refrigeration system from scratch.

In the range of average temperatures, i.e. from 0 to +12C on CO2, we have power from 3 kW to 3MW, which corresponds to facilities with an area of ​​15 to 15,000 m2. In the low temperature range (-18 to -24C), the available power ranges from 3 to about 800 kW, i.e. chambers from 15 to 4,000 m2. It should be noted that there is a possibility of further expansion of the available cooling capacities.

The total cost of the refrigeration system consists of:

– CAPEX – purchase price

– OPEX – operating costs consisting of electricity consumption and servicing

– Risk – the likelihood of unforeseen costs in the future or the construction of an installation that does not meet the Customer’s requirements. We will not take risk into account in this column -> although managing it properly can be very profitable

As the most profitable in the ESMS, we mean the installation with the lowest total CAPEX + OPEX costs for 10 years. As I will show below, BEP (Break Even Point) can and should be much less than this time.

Below I have presented a comparison of electricity consumption by the most popular refrigeration systems.

Assumptions MT: 1000 kW, LT: 200 kW

  • The r448a system is based on separate MT and LT aggregates, working on good parameters, such as those set in the facility after optimization, which I wrote about in an earlier column.
  • r744 is a basic booster with parallel compressors
  • R744 – ejectors. It is equipped with liquid and gas ejectors

If we take r448 system energy consumption = 100% as a reference, r744 primary refrigeration will use 27% less energy and r744 with ejectors 34% less energy. This corresponds to annual savings of PLN 525,000 and PLN 658,000.

Additional costs incurred for more energy-efficient systems will be recouped after 2.4 or 2.7 years.

Other energy-saving technologies to mention:

  • Floor heating freezes with glycol heated by heat recovery from the refrigeration system
  • Defrosting with glycol heated by heat recovery from the refrigeration system. It is also a very effective method, especially in cold stores.
  • Installation of air curtains

Formal issues.

Pursuant to the regulation of the EU Parliament 517/2014, from January 1, 2022, refrigerants such as the above-mentioned r448a must not be used in commercial installations. I leave the interpretation of “commercial installation” to the reader and officials.

Therefore, it is optimal to install CO2 – r744. At this point, I would like to warn the reader against simplifying the choice of refrigeration system to the simple term “CO2”. Unfortunately, in my practice, I see projects that have more in common with sparkling water than with energy efficiency, and the reason for this is both too poor definition of technical requirements and too (naively) lowering CAPEX.

That’s why I emphasize: energy-efficient refrigeration must not only be CO2, but also well designed and carefully made! Like a banana…

Food logistics – too much energy bills?

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One of the business areas in which there is still great development potential in Poland is food logistics. A part of this area are logistics centers with cold rooms and freezers, often with an area of ​​many thousands of m2. These facilities are equipped with cooling devices, the energy consumption of which is often close to 80% of the energy consumption of the entire facility. Such a large share in the electricity bill means that the financial result of the entire project depends on the energy efficiency of the cold.

The topic of cold in logistics is very broad, so I will divide it into many parts, in which I will write about, among others:

  • General principles of designing refrigeration systems in logistics
  • Existing facilities on F-gases – does the old technology have to consume a lot of energy?
  • Designing new facilities – what technology is optimal?
  • Future trends that need to be implemented today

The following content is a summary of my experience gathered during the implementation of many projects in many European countries, both for corporate and individual clients.

Let’s start!

Food logistics – too much energy bills? General principles of designing refrigeration systems in logistics

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Industrial refrigeration systems are a typical example of form serving function. Typically, the entire facility is architecturally designed so that the flow of goods is optimal. That is, only in one direction while maintaining the refrigeration sequence.

As a refrigeration expert, I focus on temperatures and not on ISO, SANEPID, or other issues.

A typical object is shown in the diagram below.

A typical logistics center will have the following zones:

  • Receipt of goods

    Goods after transport are unloaded into this zone

  • Refrigerators for storing goods

    Due to practical factors, two or more cold stores are often designed. This is of particular importance when the stored goods require different storage temperatures or humidity.

  • Freezer for storing goods

    Due to the large difference in temperature between the cold store and the rooms to which the gates lead, it is good practice to use vestibules

  • Delivery of the goods

    Goods prepared for release are temporarily stored in this zone.

Refrigeration balance
There are two methods of determining the required cooling power for logistics centers. Academic and factor. In the academic method, I count all the heat profits for a given room (walls, open gates, goods, machines, lighting, etc.). However, it is often difficult to determine in advance what the flow of goods will be in the future, which is why the coefficient method is also used. It results from the experience of the designer A consists in multiplying the coefficient by the volume of the room. For correct calculations, both of these values ​​should be equal and contain a certain supply.

Construction of premises
The main material for the partitions of refrigerated rooms is a sandwich panel made of polyurethane or glass wool (simplification). Rooms with temperatures above 0C do not require insulation of the substrate. However, one should take into account the risk of dripping moisture on the floor in adjacent uncooled rooms. This problem should be solved at the design stage. It is good practice for cold storage to be built in the “box in box” technology. In the case of rooms with an area of ​​more than 1000 m2, it is good practice to use insulation panels with a minimum thickness of 100 mm.

In the case of a cold store, it is necessary to use the “box in box” technology and to insulate and protect the floor against frost. Typically, a sandwich panel with a thickness of 160 to 200 mm is used.

Refrigeration installation
In each cooled room, air coolers are installed, adapted in terms of their construction and parameters to the logistics equipment (shelves, robots, etc.) and in locations ensuring optimal air flow.

There are many technologies for “transporting cold” to air coolers. Most often, glycol or direct evaporation of the refrigerant is used.

Although it is possible to install external chillers, it is good practice to build a machine room. This room should contain all cooling units, power and control cabinets for units, tanks for recycled hot water, etc. Gas-coolers or condensers are installed in the immediate vicinity of the engine room or on its roof.

The engine room should have drains in the floor and large doors that will allow easy work.

Between cooling units and air coolers, pipelines are installed to transport glycol or refrigerant.

Above, I have described in a very basic way the main elements of the refrigeration system. The technology used, insulation thickness, pipeline diameters, and selection parameters of all components will affect the ease of use, failure-free operation and, above all, energy consumption of the constructed installation.

The technologies available today vary greatly in terms of running costs. I am talking about a nearly two-fold difference, which in the case of the largest facilities will translate into millions of zlotys in electricity bills each year. As of the date of writing this column, the payback of high energy efficiency technologies compared to the simplest is at the level of 2 years.

The “late adopters” trap and energy savings

Electricity (and gas) prices are reaching historically unprecedented levels.

You can read about it in BusinessInsider, but also in most of the business press.

They are often so high that in some industries there is doubt as to the profitability of further operations.
This is particularly visible in manufacturing industries – high-energy industries such as: production of cement, plastics, food, etc.

As the map above shows, Polish industry is uncompetitively energy-intensive. Since the beginning of the market economy in our country (90s), Poland saved itself with low labor costs, reasonable taxes and the possibility of subsidies or reliefs. As a result of development, however, it was a matter of time to reach the level of equilibrium where the sum of “advantages and disadvantages” of production in Poland would be equal to the economies of the old Europe. In my opinion, we have reached this level, or even (with momentum) we are crossing it.

At the same time, according to the opinion of the business press, there is a lot of money on the market at least since the mid-2010s.

In my opinion, now is the last moment to spend this money wisely, and broadly understood ENERGY EFFICIENCY has been, is and will be the best investment.

Unfortunately, money does not seem easy for activities related to energy efficiency. Such investments involve allocating additional funds now for future benefits. Benefits burdened with technical, market and legislative uncertainty. And unfortunately, sometimes also lack of understanding and common opinions.

What if we don’t undertake the transformation? Transformation on a Macro scale – i.e. national, but also Micro – each enterprise separately.

A few years ago, at a refrigeration industry conference, I spoke about the “late adopters trap.”

According to this scheme, financial stocks appear in the company as a result of good business on the revenue side (sales) and too cautious investments in improving production. In this case, investments in increasing energy efficiency. Temporarily low investments make the profit in the company even greater than in the competition. However, over time, competition investing (in energy savings) begins to reap the fruits of previously spent money. These fruits are lower operating costs that allow you to lower prices or act faster/better/etc. As our competitive advantage diminishes, our financial inventory shrinks until we can no longer afford “wise investments. What can happen then -> see the picture above.

At that time, this trap consisted in the need to change the refrigeration technology that would adapt the client to legal requirements and give significant energy savings. Unfortunately, a few entrepreneurs fell for it.

Now the whole economy can get caught – We must act!

AI in refrigeration – new issue of CH&K

Artificial Intelligence in refrigeration – is there room for it?

As an auditor and designer of refrigeration installations, I sometimes explain to clients how cooling device controllers work. I often refer to the thermostat in the iron – on / off. However, this is a far-reaching simplification, because the controllers available on the market use PID systems, i.e. proportional, integrating and derivative modules. Such control is already partly “smart”. But you can go one step further – a big step.

I am going to consider whether learning protocols, often referred to as artificial intelligence, can be used in our industry.

I see the following fields of action;

Cold receivers in terms of comparing their normal operation to temporary operation. Specifically, we are talking about the valve opening time, defrosting time and the curve of reaching the set temperature, the required evaporation temperature in the case when it is variable. Predicting the load of individual rooms or furniture in the context of, for example, goods or shipments.

Air handling units, chillers and gas coolers;

Compressor working time and required pressure curve, gas cooler fan working time, reaction to weather, advanced operation with multiple energy tariffs.

Could refrigeration follow the path already followed by district heating – I think it should.