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E-mail
zzcc8162@zzgwsit.cn
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Address
1119 Science Avenue, Shangjie District, Zhengzhou City
Zhengzhou Changcheng Technology Industry and Trade Co., Ltd
zzcc8162@zzgwsit.cn
1119 Science Avenue, Shangjie District, Zhengzhou City
1. Temperature range:
o mustcoverThe temperature required for the process.
o Lower limit of refrigeration: What is the lower limit temperature required for the process? (such as-30°C, -50°C, -80°C?). The lower limit temperature of the equipment should bebelowProcess requirements (reserved margin).
o Heating upper limit: What is the upper limit temperature required for the process? (such as150°C, 200°C, 250°C）. The upper limit temperature of the equipment should beaboveProcess requirements.
2. Temperature control accuracy and stability:
o Accuracy: The precision requirements for temperature control in the process (such as±0.5°C, ±1°C, ±2°C）. Synthesis reactions and crystallization usually require±1°CWithin.
o Stability: The ability to maintain a set temperature for a long time is equally important as accuracy.
3. Circulating pump performance:
o traffic Adequate circulating flow is the key to ensuring heat transfer efficiency. Need to meet the requirements of the jacket/The resistance requirement of the kettle wall. General advice 15-40 L/min The flow range is suitable for most small and medium-sized glass reaction vessels（1L-50L）.Insufficient flow is a common cause of temperature control failure!
o Pressure (head): The ability to overcome resistance in pipelines, valves, and jackets. Ensure the pump'smaximum head>systemtotal resistance.
o Material: The pump head and seal must be resistant to the medium and temperature（316LStainless steelPTFE/FFKMSealed).
o Type: Magnetic drive pump (leak free) is a commonly used choice.
4. Interface and Connection:
o Interface size: Circular inlet and outlet dimensions (such asG1/2', G3/4', G1'）It needs to be matched with the jacket interface of the reaction vessel. Mismatch requires adapter conversion.
o Pipeline material: Temperature resistant and medium resistant (commonly used silicone tubingPTFEPipe, metal hose). Try to keep the length as short as possible and ensure proper insulation to reduce heat loss/Loss of cooling capacity.
5. Security protection:
o overtemperature/Low temperature protection: Independent multiple hardware protections.
o Low liquid level protection: Prevent dry burning of heaters or pumps.
o pressure/Pressure relief device: Closed systems require safety valves/Expansion tank.
o Leakage protection: Standard configuration.
o Explosion proof requirements: If dealing with flammable and explosive solvents, the entire machine or key components must comply with the corresponding requirementsExplosion-proof rating(such asEx d IIB T4 Gb）.
6. Control system and functions:
o User interface: Clear and easy to operate, displaying set temperature, actual temperature, pump speed, alarm information, etc.
o Program control: If multiple heating stages are required/cool down/Insulation program, select programmable model.
o Data recording: Record temperature curves and events, support export（USB, RS232, Ethernet）. comply withGMPData integrity requirements (if necessary).
o communication optionalModbus, ProfibusIntegrate the interface into the upper computer system.
7. Brand and Service:
o Choose a reputable brand in the field of laboratory temperature control.
o Consider the speed of after-sales service response, spare parts supply, and technical support capabilities.
Cooling capacity (cooling capacity) is the most critical parameter for selection, and it is necessary to ensure the temperature control equipmentActual available cooling capacity>Maximum heat load of the systemUnderestimating the heat load is the main reason for the inability to achieve low temperatures or slow cooling.
1. Through the kettle wall/Heat leakage of the jacket（Q1）：
o This isThe most important and often underestimatedThe heat load, especially when there is a large temperature difference between the target temperature and the environment.
o Calculation formula: Q1 = A * U * ΔT
§ A:Jacket heat exchange area(m²).
§ U:Total heat transfer coefficient(W/m²K)This is a difficult point, depending on:
§ Glass wall thickness and thermal conductivity.
§ Flow state of the medium inside the jacket (laminar flow)/Turbulence).
§ Material status inside the kettle (static)/Stir).
§ External environment of the kettle (static air)/Fume hood).
§ Estimation reference:
§ For a typical double-layer glass reactor in air,U The value range is roughly within 10 - 25 W/m²K.
§ ΔT:ambient temperature-Target cooling temperature(K)For example: ambient temperature25°C, target-20°C, thenΔT = 25 - (-20) = 45K (or45°C).
2. The heat capacity of the cooling material itself（Q2）：
o The amount of heat required to remove the material from its initial temperature to the target temperature.
o Calculation formula: Q2 = (m * Cp * ΔTmaterial) / t
§ m:Material quality(kg).
§ Cp:Specific heat capacity of materials(J/kgKorkJ/kgK)Common solvents have specific heat capacities~1.5-2.5 kJ/kgK (Water is4.18 kJ/kgK). Available when unknown2.0 kJ/kgKestimate.
§ ΔTmaterial:Initial temperature of material-Target cooling temperature(Kor°C).
§ t:Required cooling time(second)This is the key! How long do you want to use to lower the material from the initial temperature to the target temperature? The faster the requirement, the greater the instantaneous cooling capacity needed.
3. exothermic reaction/Heat absorption（Q3）：
o If the process itself has significant exothermic or endothermic reactions, it must be considered.
o estimate:
§ If the reaction is intense and releases heat,Peak heat release power must be measured through small-scale experiments or conservatively estimated based on experience.
§ When there is no specific data,Considering the maximum potential heat release powerOr reserve a large margin. This is the main reason for the uncontrolled reaction caused by insufficient cooling capacity!
o Example (conservative estimate): Assuming a moderately exothermic reaction, the estimated average exothermic power is100WThen Q3 = -100 W(Cooling requires additional removal of this heat).
Q_total_max = Q1 + Q2 + Q3
· Note:
o Q1 It exists continuously.
o Q2 It only exists during the cooling phase and is the instantaneous maximum value (maximum at the beginning of cooling).
o Q3 Depending on the reaction process, take itpeak.
· Calculate harsh working conditions: Identify the maximum combination of heat loads that may occur simultaneously. Usually, two situations are considered:
1. Rapid cooling stage: Q1 + Q2(peak)(Assuming that the reaction has not yet started or the heat release is not significant at this time).
2. Peak stage of exothermic reaction: Q1 + Q3(peak)(Assuming that the material temperature has stabilized at this point).
o Calculated based on these two scenarios Q_total_max inLarger valueAs a basis for selection.
P_req = Q_total_max * Safety_Factor
· safety factor(Safety_Factor)： crucial! Used for compensation:
o Estimation errors in calculations (especiallyUValue, exothermic reaction, material properties).
o The performance of the equipment deteriorates over time.
o The ambient temperature may be higher than the design value.
o Media aging, slight blockage of pipelines, etc.
o Recommended safety factor:1.3 - 1.5 (namely30% - 50%margin)For critical processes or situations with high estimation uncertainty, it is advisable to take 1.5 Even higher.
· Actual available cooling capacity: InTarget low temperatureandYour actual ambient temperatureThe cooling capacity that the equipment can provide.This data must be requested!
o The cooling capacity decreases sharply as the evaporation temperature (approximate target temperature) decreases (compressor efficiency decreases).
o The cooling capacity decreases as the condensation temperature (affected by ambient temperature) increases.