Tunnel freezers, dry freezers, cooling trays, and spiral freezers. Cryogenic freezers come in all shapes and sizes, with their specific advantages, disadvantages, and design specifications.
As an end user, how do you choose the best cryogenic freezer for your product and location? And what does choosing a specific freezer entails for its installation and connection? Read on for detailed answers to these questions.
What is a cryogenic freezer?
Simply put, a cryogenic freezer is a freezing system that uses a cryogenic liquid to cool a substance. Many of these freezing systems use liquid nitrogen as the refrigerant. With a temperature as low as -196 °C, this cryogenic liquid freezes most substances at lightning speed.
Compared to conventional freezing techniques, the cryogenic freezer has some significant advantages when freezing food or biological materials. For example, the freezing process is faster. At the same time, less dehydration and bacterial growth occur, and the structure and form of the frozen material is better preserved.
All these advantages are ideal for preserving food in the food industry as well as biological materials in the medical and pharmaceutical industries. These are the industries where we find most cryogenic freezers.
We would love to show you what the ultimate cryogenic freezer looks like; unfortunately, it does not exist. As indicated earlier, a cryogenic freezer can come in endless forms; some examples are:
- The tunnel freezer, through which large quantities of food are passed for highly efficient and rapid cooling.
- The freeze dryer for preserving biological and biomedical materials and foods.
- Immersion freezers in which food products are frozen individually and quickly by immersing them in liquid nitrogen. An example of an immersion freezer is the Demaco cooling tray for the food or automotive industry.
- Spiral freezers in which food products are led in a continuous process on a large spiral through a freezer cooled with liquid nitrogen.
- Cryogenic freezers for sample storage are mainly used in the medical industry to cool biological samples safely using liquid nitrogen.
A cryogenic spiral freezer used in the food industry
Selecting the proper cryogenic freezer
When an end user makes the decision to purchase a cryogenic freezer, the first thing that needs to be determined is what this cryogenic application must be capable of. Some crucial questions that come into play are:
- What product is being frozen? Is it for specific foods, biological materials, or pharmaceuticals? Will the freezer be used to freeze one or several products?
- How fast should the product be frozen? Some materials need to be cooled as quickly as possible, while others can be damaged by cooling them too quickly. In the latter case, a control rate freezer is often chosen.
- How much product will be cooled at a time? The more quantity of a material or the larger the product, the more heat enters the freezer.
- To what temperature should the product be cooled?
Cryogenic sample storage in the medical industry
Design specifications for the system
Once a cryogenic freezer is chosen, installation and connection follow. The freezer is brought to the site and connected by an expert to a storage tank or dewar containing liquid nitrogen (or another cryogenic liquid).
How it works; In addition to specific functionalities, each cryogenic freezer has certain requirements. These requirements mainly relate to the liquid gas supply that allows the freezer to function optimally.
Therefore, among others, the installation technicians will ask the following questions:
- How many liters of liquid nitrogen (or possibly another liquid gas) does the freezer require per hour (what is the flow rate)?
- Does the freezer have its own fill valves, or do they still need to be installed?
- What operating pressure is required for the freezer to function?
- Should the used cryogenic fluid be 100% free of gas bubbles?
- What are the safety requirements? For example, is O2 detection in the area required?
Based on this data, a cryogenic infrastructure is built that perfectly fits the cryogenic freezer as well as the user’s requirements and needs.
A cryogenic infrastructure including vacuum insulated transfer lines that direct liquid nitrogen from a storage vessel to a cryogenic freezer
Demaco is a cryogenic infrastructure supplier
At Demaco, we work day in and day out to design and install the best cryogenic infrastructures for endless applications, including cryogenic freezers.
Within various industries, we have commissioned freezers of all shapes and sizes in various locations over the past decades. Our focus is always on the freezer’s design specifications and industry guidelines.
We consider aspects such as flow rate, working pressure, and the proper supply of cryogenic liquid. Our quality improvement products ensure a cryogenic liquid free of gas bubbles.
Typically, an infrastructure for a cryogenic freezer consists of the following components:
- Vacuum-insulated transfer lines, which ensure that (for example) liquid nitrogen from a storage tank or dewar reaches the cryogenic freezer. Vacuum technology offers, by far, the best insulation for cryogenic liquids. It minimizes heat leakage and ensures that the cryogenic liquid reaches the freezer in optimal quality.
- Quality improvement products include, for example, a phase separator, degasser, or subcooler. These products allow the quality of the liquid gas to remain high and help to establish the required working pressure.
- Welding couplings, or Johnston couplings, connect the vacuum-insulated pipe sections to each other and to other components of the infrastructure.
- Any fill valves, either desired or necessary, within the system – and emergency valves and shut-off valves.
- Any additional safety measures, such as an O2 detector in the facility.
We provide a meticulously designed infrastructure that ensures that each cryogenic freezer will operate optimally.
Would you like to know more?
Do you have questions about installing and connecting a cryogenic freezer? Or would you like to know more about Demaco’s products and services? Feel free to contact us or check out our products and projects.