how to get maximum refrigeration efficiency and energy savings ROI’s
refrigeration energy savings
To achieve maximum refrigeration energy efficiency and ROI, several strategies can be employed:
- Lowering Compression Ratio: Reducing the overall refrigeration system compression ratio is key. This can be done by maintaining lower condensing pressures and higher suction pressures within the system.
- Regular Maintenance: Cleaning air filters and coils, ensuring proper refrigerant charge, and regular system checks can prevent efficiency losses.
- Liquid Pressure Amplification (LPA): Installing LPA liquid refrigerant pumps in the system’s liquid line delivers 100% liquid refrigerant to the expansion valves, eliminating flash gas and enhancing system flow.
- Floating Head Pressure: Implementing floating head pressure control allows the system to operate at the lowest possible pressure for current ambient conditions, improving efficiency.
- Flash Gas Suppression: To eliminate liquid line flash gas, an LPA pump can be installed to suppress the flash before it reaches the system expansion valves. Flash gas does not contribute to cooling and thus represents a loss of efficiency.
- Improved System Design: Designing systems with shorter liquid lines, minimal bends, and proper insulation can prevent flash gas formation or install an LPA pump to overcome liquid line pressure drop.
- Sub-cooling: Increasing the level of sub-cooling ensures that the refrigerant remains liquid until it reaches the expansion valve, preventing flash gas or install an LPA pump to deliver 100% liquid to the expansion valves regardless of liquid line pressure drop.
By combining these methods, especially the use of HY-SAVE’s LPA technology, significant energy savings can be achieved, leading to a better return on investment. These improvements not only reduce power consumption but also enhance the overall performance of the refrigeration system, providing more cooling with less energy, which is particularly beneficial in the commercial retail industry. For detailed guidance on implementing these strategies, contacting HY-SAVE or a refrigeration efficiency expert is recommended.
What is flash gas?
Flash gas formation in refrigeration systems is a phenomenon where the refrigerant, intended to be in liquid form, partially vaporizes before it reaches the expansion valve. This can occur due to heat absorption or pressure loss in the liquid line. The presence of flash gas is undesirable as it reduces the efficiency of the refrigeration cycle; the refrigerant in gas form does not contribute to cooling but still requires energy to be circulated by the compressors.
Regarding the relationship between flash gas by weight and volume, as system head pressures are reduced, the percentage of flash gas by weight does indeed expand substantially. For example, 1% flash gas by weight at a condensing temperature of 38°C can expand into 20% flash gas by volume when system head pressures are reduced to condense at 15°C. If the flash gas by weight is 3%, then 42% of the liquid line could be filled with gas, leading to inefficiency and increased operational costs.
The LPA (Liquid Pressure Amplification) pump saves energy by increasing the pressure of the liquid refrigerant in the liquid line, which allows for 100% pressure sub-cooled liquid to be delivered to the cooling coils. This process reduces the system head pressure to a minimum, which in turn lowers the compression ratio and the energy required for compression.
The extent of energy savings achieved with an LPA pump depends on the initial inefficiency of the refrigeration system and the performance gains after the LPA pump installation. In a case study from a dairy farm in Northern Ireland, the implementation of Liquid Pressure Amplification technology in refrigeration systems showed potential for reducing energy consumption in retrofit applications. The study demonstrated that the use of LPA, in conjunction with other measures like liquid injection, can lead to significant energy savings and improved system performance.
By maintaining the refrigerant entirely in liquid form up to the expansion valve, the LPA pump prevents the formation of flash gas, thereby enhancing the efficiency of the refrigeration system.
Case Study
School of Engineering and Design, Brunel University, Uxbridge, Middlesex,
Hadawey, S. A. Tassou*, Y. T. Ge
Case study, dairy farm, northern Ireland, Liquid Pressure Amplification in Refrigeration Systems – Potential for Reducing Energy Consumption in Retrofit Applications