The industrial refrigeration market is characterized by continuous growth and innovation, making it crucial to stay informed about its components to remain competitive. Regardless of the industry—be it food, medical, construction, or mining—product manufacturing often necessitates a refrigeration process.
A refrigeration system does not “create cold” (which is thermodynamically impossible) but rather removes heat from a body and expels it. This is achieved by manipulating a refrigerating substance (refrigerant) that constantly changes between liquid and gaseous states, absorbing and evaporating heat in the process.
Every refrigeration process follows a basic, infinite cycle comprising four key sections:
Compression > Condensation > Expansion > Evaporation
To execute each part of this cycle, various interconnected components and accessories are utilized. Below is an explanation of their operation:
1. Compressor
The compressor handles the refrigerant in its gaseous state, compressing it to increase its pressure and temperature. The choice of compressor depends on the specific project requirements. Common types used in the industry include:
- Piston Compressors: These are compact, semi-hermetic units suitable for various refrigerants, offering versatility.
- Helical Screw Compressors: Designed for industrial refrigeration and air conditioning, these emphasize energy saving and sustainable efficiency.
- Screw Compressors: Intended for commercial and industrial use, they are compatible with HCFC/CFC refrigerants and provide efficient power regulation.
- Scroll Compressors: Composed of a fixed scroll and an orbiting scroll. The orbiting scroll, attached to the crankshaft, creates a series of refrigerant gas pockets that are compressed as they move between the scrolls, increasing pressure.
- Hermetic Compressors: Widely accepted and classic in the industry, used in air conditioning systems, heat pumps, and refrigeration due to their broad applicability.
- Semi-Hermetic Compressors: Designed for systems requiring high-temperature performance, even at low evaporating temperatures down to -40°F (-4.5°C).
Major Compressor Brands Recommended by Froztec: GEA, Bitzer, and Copeland-Emerson.
For guidance on selecting the right compressor, you can refer to the blog: “For non-engineers: Basic points for choosing a compressor.”
2. Condenser
The condenser receives high-pressure refrigerant gas and lowers its temperature, causing it to change into a liquid. When a condenser is combined with a ventilating motor and a compressor, it forms a condensing unit.
Different types of condensers are used in industrial refrigeration, depending on the project goals and industry conditions. The most common types are:
- Evaporative Condenser
- Remote Condenser
- Condensing Units (condenser + ventilating motor + compressor)
Brands considered for projects due to their quality and technological reputation: SPX Cooling Technologies and Krack.
For more information, consider reading “Refrigeration for non-engineers: Choosing your condensing unit.”
3. Expansion System
The expansion system transforms the liquid refrigerant into small, low-pressure liquid particles, similar to how an atomizer works. These small particles then absorb ambient heat and evaporate.
The expansion system primarily consists of valves. These regulate the flow of liquid refrigerant entering the direct expansion evaporator, maintaining a constant superheat of the refrigerant vapor at the evaporator’s outlet. Its main functions in direct (or dry) expansion equipment are controlling the liquid refrigerant flow into the evaporator and ensuring constant superheating at its output.
Different types of valves include:
- Thermal Expansion Valve (TXV): Controls the flow of liquid refrigerant into the direct expansion evaporator, maintaining constant superheat of the refrigerant vapor at the evaporator output.
- Solenoid Valves: Electrically operated valves used to automatically control the flow of fluids, liquids, or gases.
- Ball Valves: Control flow direction and enable closing, with port configurations that support various system requirements.
- Carter In-Line Pressure Valves: Designed to prevent compressor motor overload by limiting carter pressure to a predetermined maximum value during and after defrost cycles or normal shutdown periods.
- Evaporator Pressure-Regulating Valves: Control the evaporator temperature by indirectly controlling the evaporator pressure.
- Condenser Pressure-Regulating Valves: Used for controlling the pressure of systems with air-cooled condensers.
Major Brand in the Industry: Sporlan
4. Evaporator
The evaporation system absorbs heat by evaporating the refrigerating liquid. All refrigeration projects, regardless of size, incorporate evaporators; only their sizes, capacities, and shapes vary. Evaporators implemented in industrial refrigeration systems come in diverse sizes and capacities, allowing for selection based on the specific system performance requirements.
Krack evaporators are considered industry leaders due to their technology, environmental considerations, and energy consumption efficiency.
5. Refrigerant
A refrigerant is a chemical substance whose properties enable it to absorb heat from one body and transfer it to another, thereby causing a temperature reduction. There are two main categories:
- Synthetic Refrigerants:
- Hydrofluorocarbons (HFCs)
- Hydrochlorofluorocarbons (HCFCs)
- Chlorofluorocarbons (CFCs)
- Natural Refrigerants: These are alternatives to synthetic refrigerants because they do not damage the ozone layer and have a very low Global Warming Potential (GWP). Examples include:
- Carbon dioxide
- Ammonia
- Hydrocarbons
If you’re interested in this topic, you can read more about “Natural refrigerants categories.”
How to Start Quoting Prices for Refrigeration Systems
There isn’t a single, specific way to begin quoting prices for a refrigeration system for your business. The process typically starts with specialized consultancy from a refrigeration expert who will assess the necessary technical aspects.
However, the engineering process for a project involves considering important elements such as return on investment, return on net assets, and parametric costs.
Aspects to be Evaluated:
- Engineering Phase: This phase involves assessing needs and project viability. An estimated cost is developed based on similar projects, depending on the company undertaking the work. The executive project is typically quoted at $\text{20%}$ to $\text{30%}$ of the total parametric cost.
- Thermal Charge Level: Evaluating thermal charges in an industrial refrigeration system is crucial. This study helps in selecting appropriate walls and insulating materials, which impacts long-term savings by reducing energy expenses, even if it means a greater initial investment.
- Life Cycle of the Refrigeration System: A thorough financial analysis is essential for significant investments in refrigeration systems. This analysis must consider energy costs, maintenance costs, and environmental impact costs. The initial cost is determined by selecting the most efficient equipment, best materials, and manufacturing methods. It’s important to compare investment expenses for preventive and predictive maintenance versus corrective maintenance. Ideally, the expenses generated by both, versus the cost of equipment downtime, should be approximately equal.
This overview covers some basic points of the main components and accessories in refrigeration. Their specific uses vary depending on each refrigeration project. Remember that only a refrigeration expert can recommend the optimal equipment or systems for your particular project.