How to make the clean room more energy-efficient?

1. Low Section Wind Speed ​​Design Cross section wind speed is the speed at which air passes through the filter or heating/cooling coils in air handling components.

Most engineers design air handlers to 500 inches per minute based on "experience." Although this design saves time, it increases operating costs. In low profile wind speed designs, larger air handlers and smaller fans are used to reduce the air flow rate and reduce energy consumption and life-cycle costs.

The pressure drop determines the energy loss of the fan. From the “square rule”, it can be known that the pressure drop is proportional to the square of the speed drop. If the section wind speed decreases by 20%, the pressure drop will drop by 36%; if the section wind speed decreases by 50%, the pressure drop will drop by 3/4. According to the “cubic rule”, the change in fan energy consumption is proportional to the cube of flow change. If air flow is reduced by 50%, fan energy consumption will drop by 88%.

As a result, larger size air handlers, larger filters, and coil areas consume less fan power, allowing smaller fans and motors to be used. Small fans add less heat to the air, reducing the difficulty of cooling. Smaller coils are easier to clean and work more efficiently, so the temperature of chilled water can be higher. Filters work better and last longer at low cross-section wind speeds.

The design reduces the pressure drop of air and water and reduces the amount of cooling coil water. Streamlined design, with almost no sharp corners, reduces pressure drop by 10% to 15%.

The design can also reduce the pressure drop by a quarter. The goal is to reduce the energy loss by at least 25% and reduce the size of the variable speed fan. The optimal cross-sectional wind speed range is 250-450 ft/min, depending on usage and energy consumption.

Second, the number of ventilation clean room to maintain a certain amount of air flow to maintain cleanliness and the number of particles. The flow rate is determined by the number of air changes per hour, which also determines the size of the fan, the construction configuration and the energy consumption. Under the prerequisite of maintaining cleanliness, the reduction of air flow rate can reduce construction and energy costs. A 20% reduction in the number of air changes can reduce the size of the fan by 50%. The cleanliness of the air is more important than saving energy, but the latest research results have been documented to reduce the cost of cleanliness.

There is no consensus on the optimal number of ventilations. Many of the principles are outdated, based on old ideas, using inefficient air filters. The survey shows that the number of ventilation changes recommended by the ISO Class 5 clean room is from 250 to 700.

A national laboratory in the United States is currently defining the ISO Class 5 cleanroom standard. Studies have shown that the actual number of air changes is in the range of 90 to 250 - much lower than the operating standards, and will not affect production and cleanliness. Therefore, it is recommended that the number of air changes in the ISO Class 5 clean room is approximately 200, and the conservative limit is 300.

Third, the motor efficiency motor consumes most of the clean room power. A continuously operating motor consumes a lot of electricity every month. Appropriately improving efficiency and appropriately sizing, after refurbishment, economic results are mostly good. With a few percentage points of efficiency, profits can increase.

Using high-quality, high-efficiency motors does not necessarily cost too much. High efficiency means minimal, and the load is reduced as much as possible before changing the size of the motor. When the output changes, the use of variable speed drives can increase operating efficiency.

Fourth, variable speed drive freezer variable speed drive refrigeration can save a lot of energy and money. Many clean room designers and operators believe that there is no need to use a variable speed drive chiller because the load is usually constant and multi-level chiller units are usually controlled to operate at high loads. However, a constant load of the freezer usually operates below full load. Variable speed drive chillers typically operate at 90%-95% of full load to save energy. A 1000-ton refrigerator operates stably at 70% of its full capacity. If a variable-speed drive is used, it can save between $20,000 and $30,000 per year. According to the manufacturer's data, the price of electricity is 0.05 US dollars/kWh, so that the cost can be recovered in about one year.

Multi-stage chiller chiller units rarely operate at high loads. Normally, the on-site load usually does not exactly match the energy level change of the unit. Many operators operate additional chillers for reliability. Once a chiller fails, other chillers can immediately replenish and take over its entire load. Therefore, chilled water chillers often allow the chiller to be between 60% and 80 kW of cooling capacity. % operating.

When purchasing a new freezer, it is worthwhile to purchase a variable speed drive refrigerator. Using a variable speed drive refrigerator can reduce energy consumption while allowing other chillers to operate reliably. There are many studies and experiments demonstrating that the effect of variable speed drive refrigerators is very good. For more than two decades, variable speed drive refrigerator manufacturers have created more reliable products for use in new and upgraded cleanrooms.

5. Dual-temperature refrigeration cycle The refrigeration system is usually designed to withstand the maximum load regardless of whether the maximum load occurs frequently or not. The temperature of the chilled water in the refrigeration cycle in the process is determined by the extreme thermal load that only occupies a small part of the total load. This is just one or two of many situations. This will result in excess refrigeration capacity and inefficiencies in the event of insufficient load. When the temperature of the supplied chilled water is low, the working efficiency of the refrigerator is also very low. On average, the chiller supply temperature increases by one degree Fahrenheit and the freezer efficiency increases by more than one percentage point. If you divide the load and provide two different temperatures of chilled water, the work efficiency will be higher