Optimizing Refrigeration Systems in the Dairy Industry

Introduction

The dairy industry is one of the most energy-intensive industries owing to its energy requirements for refrigeration, milk cooling, and process heating. Dairy industries collect milk from both cooperative and private dairies. Milk is processed in dairy into products such as packaged flavored milk, ghee, butter, curd, khoa, milk powder, and paneer. The dairy industry uses two main types of processes: heat treatment of milk to increase shelf life and dehydration of milk to produce products such as butter, hard cheese, and milk powder.

Production process

Production processes in the dairy industry typically involve several stages, from milk collection to the final product packaging. The general process steps in the dairy industry include raw milk collection, quality control, and high-temperature short-time (HTST), which is the most commonly used method for pasteurization, cream separation, standardization, homogenization, packaging, storage, and distribution.

Process Refrigeration systems

Refrigeration plays a crucial role in the dairy industry to maintain the freshness and quality of dairy products, particularly milk. Refrigeration systems cool the milk to temperatures below 4°C rapidly, inhibiting bacterial growth and preserving its taste and nutritional value. Refrigeration is integral to various dairy processing steps, such as pasteurization, homogenization, and separation Cheese-making involves precise temperature control during fermentation, curd formation, and aging. Refrigeration is used in butter-making processes to cool cream and separate butterfat from buttermilk. According to BEE, the dairy industry should improve the energy performance of the refrigeration system by optimizing various operating parameters and reducing specific energy consumption (SEC) levels. These include the reduction of various energy losses occurring in the refrigeration system through routine inspection and maintenance and keeping key operating parameters within specified limits as prescribed by the OEMs.

Energy-Efficient Solution for Dairy Refrigeration

Improving energy efficiency in the dairy industry is essential for reducing operational costs, reducing environmental impact, and ensuring sustainable production. Conducting regular energy audits to identify areas where energy is being wasted and analyse energy consumption patterns to pinpoint opportunities for improvement.

• Pre-cool warm, fresh milk using a well/groundwater to reduce the energy requirements of the refrigeration system used in the milk chilling center.?
• Avoid bringing warm products and warm air from outside into the cold room and have proper sealing arrangements, use strip curtains to keep away from warm air and moisture.
• Operate cold storage at the highest possible temperature recommended for the product type, which should reduce the load on the refrigeration system.
• Provide insulation of suitable type, size, and thickness to reduce energy loss from uninsulated valves, bare pipes, defective insulation of refrigeration system, etc. Provide sufficient thickness of insulation to maintain surface temperature above the dew point temperature of ambient air.
• Ensure matching of plant load with refrigeration system capacity, as part load operation will lead to higher specific energy consumption.
• Manage the air-conditioning of process floors to only essential zones and reduce loads with potential options such as window shades, and low thermal mass walls.
• Replacement of inefficient reciprocating compressors with new energy-efficient screw compressors and Installation of an automatic tube cleaning System for Heat Exchangers
• Automation of cold room indoor units and replacement of fans with highly energy-efficient fans

Approach to developing an energy-efficient refrigeration system: design and equipment selection.

Interventions designed to boost energy efficiency in the design of equipment and systems can be effectively implemented in both existing and new dairy packing areas. These strategies include the adoption of low-energy evaporative cooling systems for maintaining optimal temperatures within the packing area, the selection of refrigerants that have not only minimal environmental impact but also exhibit superior thermal efficiency, and the choice of energy-efficient appliances for pre-cooling operations and cold room management. Additionally, integrating sub-metering for specific energy consumers, such as pre-cooling processes, staging cold rooms, and dairy processing machinery, can lead to more precise energy monitoring and management. Further enhancements involve the use of electronic expansion and subcooling techniques to improve refrigeration efficiency. Implementing energy management systems equipped with advanced control and automation capabilities is also recommended to efficiently oversee refrigeration units and control indoor environmental parameters in the dairy industry, aligning with recommendations from the Bureau of Energy Efficiency (BEE).

Conclusion

By leveraging energy-efficient technologies, refining processes, and incorporating renewable energy solutions, dairy producers can significantly lower operational expenses while making a meaningful impact on environmental preservation. The advantages of such initiatives go beyond economic savings, including notable reductions in greenhouse gas emissions, decreased dependency on fossil fuels, and a substantial contribution towards combating climate change. The industry needs to manage the water in cooling towers effectively to minimize microbial growth. Enhancing the energy efficiency of plants through the implementation of natural ventilators, pre-cooling of fresh milk, preventing the influx of warm air and products into cold storage areas, and the use of energy-efficient fans and compressors can lead to significant improvements. Additionally, adopting heat recovery systems to capture and repurpose waste heat from processes like pasteurization or the generation of hot water further underscores the pivotal role of energy efficiency in ensuring the dairy industry's sustainability into the future.