To save energy during cooling and maintain the cold chain, the Mönchengladbach-based technology company LWT-Airwalls offers air walls. For example, freezer rooms can be insulated from cold rooms even when the door is open.This article appeared in the "Cold store construction and operation" section of Frischelogistik magazine in January 2023.
To save energy during cooling and maintain the cold chain, the Mönchengladbach-based technology company LWT-Airwalls offers air walls. For example, deep-freeze rooms can be partitioned off from cold storage rooms even when the door is open.
When it comes to energy efficiency, many companies usually focus on saving energy to generate heat. Fresh produce logistics companies know, of course, that it is worth focusing on possible savings in cooling energy. Because, as the technology company LWT-Airwalls emphasizes, cooling is generally more expensive than heating!
One reason for this is that almost all cooling appliances are supplied with electricity decentrally. In contrast, heating is usually operated as a centralized system, predominantly with gas. If you compare the primary energy factors in accordance with the Building Energy Act (GEG) and the efficiency of a gas heating system with that of a cooling unit, the Mönchengladbach-based company's calculations show that cooling is three times more expensive than heating.
Interrupted cold chains along the supply chain can also be a source of energy loss. In the worst case scenario, products or even entire batches become unusable. In addition, air is exchanged through draughts and convection when doors and gates are open. Convection is particularly significant in deep-freeze warehouses, as large temperature differences can occur. The temperature here is often -25°C all year round and there is already a difference of 25°C at 0°C ambient temperature. In contrast, heating is rarely this high in our latitudes.
This is why a lot of energy is needed for deep-freeze and cold storage rooms. The costs for this energy remain high despite the current price caps imposed by the German government from January 2023, emphasizes LWT-Airwalls.
Doors and gates of cooled rooms should also be sealed when open, the company advises. According to the provider, the solution with an air wall system usually pays for itself after just one to three years. It is an effective way of keeping the cold in a room. According to LWT, an air wall system enables efficient temperature separation between halls, doors and gates with different temperatures and eliminates the need for constant re-cooling. The technology is versatile. For example, as a barrier between deep-freeze and cold storage rooms or cold storage rooms and rooms with normal temperatures of up to 30°C. Air wall systems are also used in high-bay warehouses with different temperature ranges.
According to LWT-Airwalls, the following combination solution can be used to seal off deep-freeze rooms from cold storage rooms: An airwall system is installed on the freezer side, in which the airwall is built up by horizontal air jets. Specially manufactured vertical pressure nozzles made of aluminum are placed to the left and right of the door.
Air wall systems are also suitable for separating the temperature between the cold room and the room at normal temperature, as shown here.
through which the air flows. The air jets meet in the center of the door and form a barrier-free wall. The entire door surface is protected from escaping freezer air. A specially designed ventilator is located externally and can be installed either visibly or concealed, depending on requirements and space.
A compact solution is installed on the "warmer side". This air wall unit blows vertically from top to bottom. The compact unit protects against "warm" air entering the freezer room. Only the upper third of the door surface needs to be sealed off, as warm air is lighter and tries to enter the room towards the ceiling.
The supplier believes that this method is an ecologically valuable alternative to competitor products in order to prevent ice forming on the door and in the area around the door, as it does not require the use of heat registers. Specially selected energy-efficient fans would achieve high levels of success and energy savings at low output.
According to LWT-Airwalls, the Federal Office of Economics and Export Control (Bafa) is also convinced by this technology and provides funding for this purpose.