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The following is an article written by myself; I warmly welcome everyone to discuss it and offer any criticism or suggestions. Introduction: Under the requirements of environmental protection and energy conservation, the power consumption of refrigeration systems is the most important factor of concern. For the operation of LNG plants, given fixed equipment costs, choosing energy-efficient and efficient process solutions is the most important way to reduce consumption and increase revenue. For air conditioning products, the energy efficiency rating is a method used to indicate the differences in their energy efficiency. The energy efficiency ratio refers to the ratio of the rated cooling capacity to the rated power (power consumption). In accordance with **relevant standard regulations, the energy efficiency ratio of air conditioners is divided into five levels: 1, 2, 3, 4, and 5. The corresponding energy efficiency ratios are above 3.4, 3.2–3.4, 3.0–3.2, 2.8–3.0, and 2.6–2.8 respectively. According to the regulations, products with an energy efficiency level below the minimum 5th level required for market access are not allowed to be sold on the market. The background color of the energy efficiency label is blue, with information such as the “producer’s name” and “model specification” displayed at the top ； The most prominent part is the middle section of the logo, which features markers for levels 1 to 5, ranging from green to red. On the left side, there is information indicating energy consumption levels, from \"low\" to \"high\", while the upper right corner clearly shows the energy efficiency level of this specific product model. The lower part of the label provides the specific values for \"energy efficiency ratio,\" \"input power,\" and \"cooling capacity.\" 1. Definition of the energy efficiency ratio of LNG refrigeration systems: An LNG liquefied natural gas refrigeration system consists of several main components such as a refrigerant compressor, condenser, J-T valve, and cryogenic tank; the refrigeration system used in the LNG liquefaction process is also a closed-loop system. As shown in the figure below: The refrigerant is compressed by the refrigerant compressor, resulting in it reaching a high-temperature and high-pressure state. It is then cooled in the condenser, thereby releasing the heat absorbed by the refrigerant. After entering the cold box, the refrigerant exchanges heat with the purified natural gas; it absorbs heat from the natural gas before returning to the refrigerant compressor for further compression, thus returning to its original state. Energy efficiency ratio = Heat Q absorbed from natural gas / Work W done by the compressor. The heat Q_absorbed from the natural gas is the sensible heat released during cooling in the natural gas liquefaction process, plus the latent heat released during the phase change process; it represents the effective heat load on the cryogenic tank. The work done by the compressor, W, is the active power of the refrigerant compressor. If for an LNG plant with a processing capacity of 300,000 cubic meters per day, the heat load of the cryogenic tank is 3171 KW and the active power of the compressor is 1000 KW, then the energy efficiency ratio of the LNG refrigeration system is 3.171. If the compressor’s power is 2000 KW, then the energy efficiency ratio is 1.58. According to the energy-saving standards for air conditioning systems, if the efficiency is below the minimum market entry requirement of level 5, which is 2.6, such systems are not allowed to be sold on the market. 2. Load calculation for the cryogenic tank in the LNG refrigeration system: The cryogenic tank is one of the key components of the LNG refrigeration system, and its load capacity is the most important factor ensuring large-scale production of LNG. In the example diagram above, the amount of heat absorbed by the cold box from natural gas per unit of time represents the load capacity of the cold box, which can be expressed in KW. The heat absorbed by the cryogenic tank per unit of time can be calculated based on the predetermined daily volume of natural gas to be processed. This calculation takes into account both the sensible heat released during the cooling process in the cryogenic tank, which is determined by the specific heat Q_s, and the latent heat Q_l released during the phase change from gaseous to liquid state of the natural gas. For example, in an LNG plant that processes 300,000 standard cubic meters of natural gas per day, using the values of natural gas density at 0.72 kg/nm3, specific heat capacity of 2156 J/(kg•K), and liquefaction temperature difference of 260 degrees, the sensible heat value can be calculated as follows: Q_sensible = 30x10000x0.72x2.156x260/(24x3600) = 1401 KW. The latent heat of vaporization for natural gas is 510.25 kJ/m3; thus, the latent heat value for 300,000 standard cubic meters of natural gas can be calculated as: Qlatent = 30x10000x510.25/(24*3600) = 1771.7 KW. Therefore, the total effective heat load of the cryogenic tank in such an LNG refrigeration system is 3171.7 KW. 3. Energy allocation design for the LNG refrigeration system: As can be seen from the cycle of the refrigerant’s state described above, the effective energy absorbed by the cryogenic tank, Q_absorbed, together with the effective power input by the compressor, W, must both be cooled by the refrigerant condenser. This process removes the additional energy Q_released from the refrigerant, allowing it to return to its original state so that the next cooling cycle can begin. Therefore, the energy Q_release from the refrigerant condenser should equal the effective heat load Q_absorbed by the cold box, plus the active power W of the refrigerant compressor: Q_release = Q_absorbed + W. If the power of the refrigerant condenser is insufficient, the result will be that the cooling capacity of the refrigeration system is inadequate, and the amount of product that can be liquefied cannot meet the desired level.