How to choose a suitable chiller for a vacuum furnace

As the core processing equipment for material synthesis, the vacuum furnace requires a temperature control system to provide heat during operation,chillerIt plays a role in temperature control in the middle. Today, Dawosi will discuss with you how to choose a suitable matching chiller. Dawosi is a technology-based enterprise dedicated to providing temperature control solutions for industry and scientific research, with a focus on chillers and temperature control equipment.

One:The heat of the vacuum furnace mainly comes from:

1.Heating element heating: the main source, especially during the high temperature stage.

2：Thermal radiation and heat dissipation of furnace shell: At high temperatures, the outer shell of the furnace body will radiate heat to the surrounding areas.:

3：Workpiece process heat release: Some reactions (such as sintering) release additional heat.:

4：Heating of auxiliary equipment: such as diffusion pumps, Roots pumps, and mechanical pumps that generate heat during operation.:

5：Conducting heat through electrodes, feedthrough, etc.

2： How toMatching steps and key parameters

Step 1: Clarify the requirements of the vacuum furnace (request from the vacuum furnace manufacturer)

This is the most important data, usually indicated on the equipment nameplate or technical agreement.

Total cooling water demand: typically in units of L/min(Rising)/Minutes) orm³/hcubic meter/Hour).

Inlet water temperature requirement: Typically required ≤25℃ or ≤30℃. This is the outlet temperature that the chiller needs to ensure.

Return water temperature requirement: Typically required ≤35℃ or ≤40℃. This is the return water temperature of the furnace body, used to calculate the temperature rise.

Work pressure requirements: usually require 0.2 ~ 0.4 MPaThe head of the chiller water pump must meet the requirements.

Water quality requirements: Generally deionized water or softened water to prevent scaling, blockage of pipelines, and corrosion of equipment. This determines that the chiller water tank and internal circulation pipeline need to be compatible.

Step 2: Calculate the required cooling capacity

Commonly used units for cooling capacity (power) kWorkcal/h（1 kW≈860 kcal/h）.

Method 1: Calculate through water flow rate and temperature difference (commonly used)

Formula: Cooling capacity（kW）=Water flow rate（m³/h）Temperature difference (℃)1.163

Water flow rate: The total flow rate required by the vacuum furnace.

Temperature difference（ΔT）Return water temperature required for vacuum furnace-Inlet water temperature. Usually taken5℃~ 10℃. For example, requiring water intake25℃， 回水35℃, then ΔT=10℃。

Example: A certain vacuum furnace requires water flow rate 5 m³/hInlet water ≤25℃， 回水≤35℃。

Required cooling capacity = 5 m³/h×10℃ ×1.163 ≈58.15 kW

When selecting, it is recommended to add20%-30%A safety margin to cope with complex working conditions, rising environmental temperatures, or equipment aging. Therefore, one can choose one70kW ~ 75kWThe chiller.

Method 2: Estimate the installed power of the vacuum furnace (rough estimate)

For a resistance heating vacuum furnace, the cooling capacity can be roughly estimated as the heating power 60% ~ 80%.

For example, a100kWThe required cooling capacity of the chiller for the vacuum furnace is approximately60kW ~ 80kWThis method is not precise and is only for reference.

Step 3: Select the type of chiller

Air cooled chiller:

Advantages: Easy installation, no need for cooling towers and cooling water pumps, only connecting water pipes and power supply, suitable for situations where water resources are scarce or it is inconvenient to install cooling.

Disadvantages: The refrigeration efficiency is greatly affected by the ambient temperature, and the refrigeration capacity may decrease during high temperatures in summer, resulting in high noise and slightly higher initial investment.

Applicable: Small and medium-sized vacuum furnaces, workshops with good environmental ventilation.

水冷式冷水机：

Advantages: High refrigeration efficiency, stable operation, minimal environmental impact, and relatively low noise.

Disadvantage: Requires supporting cooling tower+cooling water pump+Waterway system is complex, occupies a large area, and consumes water.

Applicable to medium to large vacuum furnaces with stable water sources and installation space.

For vacuum furnaces, air-cooled type is usually recommended because of its simple system, easy maintenance, and ability to ensure the cleanliness of the internal circulating cooling water.

Step 4: Focus on key configurations and features

Water pump: The head and flow rate must meet the requirements of the furnace body. Inquire about the parameters of the water pump from the supplier.

Compressor: Brand (such as Valen, Danfoss, Bitzer, etc.) and quality are key. Multi head compressors can work alternately at low loads, which is more energy-efficient.

Temperature control accuracy: Vacuum technology requires stable water temperature, which should be selectedPIDIntelligent temperature control models with an accuracy of ±1℃ or higher.

Heat exchanger: The evaporator material (preferably stainless steel) and design affect efficiency and lifespan.

Protection function:

Water flow protection: prevent water interruption during operation.

High and low pressure protection: protect the compressor.

Anti freezing protection: winter protection.

phase sequence/Phase loss protection: protects the motor.

Temperature alarm: The outlet temperature is too high/Low alarm.

Liquid level alarm: Internal circulating water shortage alarm.

Material compatibility: The internal circulation water circuit (water tank, water pump, pipeline) should be suitable for using deionized water (which may be corrosive to certain metals).

Fourth:Installation and usage precautions

4.1Location and environment: The air cooler should be placed in a well ventilated area away from heat sources and dust, ensuring sufficient space in front and behind the heat dissipation fins. The water-cooled machine needs to ensure good ventilation in the cooling tower.

4.2Pipeline connection:

Use hoses or shock-absorbing throat connections to prevent vibration from being transmitted to the vacuum furnace.

Insulate the pipeline to reduce cooling loss and condensation.

The identification of import and export pipelines is clear, and reverse connection is strictly prohibited.

4.3Water quality management:

Be sure to use deionized water or softened water that meets the requirements.

Regularly check the water quality of the water tank and replace the cooling water (recommended every time)3-6Months).

Install filters and clean them regularly.

4.4System linkage:

Connect the water flow alarm signal or normal operation signal of the chiller to the control system of the vacuum furnace to achieve interlocking protection——Only when the cooling water is normal can the vacuum furnace start heating.

Regular maintenance:

Clean the finned condenser of the air-cooled machine or the shell and tube condenser of the water-cooled machine.

Check the operating status of the compressor.

Check the pressure and flow rate of the water pump