Definition
The heating thermostatic circulation tank is a temperature control device that uses built-in heating elements and circulation pumps to make the liquid medium in the tank reach and maintain the set temperature, and convey the thermostatic liquid to the external equipment through the circulation system. It is usually composed of core components such as tank, heating system, temperature sensor, circulation pump and control system, and its main function is to provide a stable and uniform temperature environment and circulating constant temperature source for various experiments or processes.
How it works:
The heating constant temperature circulation tank works based on the principle of closed circulation and feedback control. According to the difference between the target temperature set by the user and the temperature of the medium monitored by the temperature sensor in real time, the control system calculates the control signal through the proportional-integral-differential algorithm and adjusts the power output of the heating element, so as to heat the medium in the tank. When the medium temperature reaches the set value, the system enters the holding mode to compensate for the heat loss caused by the environment through intermittent heating. At the same time, the circulation pump works continuously to evenly distribute the temperature of the medium in the tank, and can circulate the constant temperature medium through external pipelines to the reactor, rotary evaporator and other equipment that requires temperature control to realize heat transfer and exchange. The temperature control process can be simplified into a closed-loop feedback system, and the control algorithm can be expressed as:
Pout = Kp × e(t) + Ki × ∫e(t)dt + Kd × de(t)/dt
where PoutFor the heating output power, e(t) is the deviation between the set temperature and the measured temperature, Kp、Ki、KdThey are proportional, integral, and differential coefficients.
Calibration method
The key performance parameters of the heated thermostatic circulation tank mainly include temperature stability, uniformity and accuracy. Temperature stability refers to the degree to which the temperature fluctuates at a certain point in the groove over time, usually by high-precision temperature recorder at a fixed point for a long time, and its standard deviation or maximum deviation is calculated. Temperature uniformity refers to the temperature difference at different spatial points in the working area of the tank under steady state, and multiple calibration probes need to be placed at different representative positions in the tank to record the temperature of each point and calculate the extreme difference. Temperature accuracy refers to the actual deviation between the displayed temperature of the equipment and the standard temperature, which needs to be compared with the displayed value of the tank body using a standard thermometer calibrated by the measuring mechanism. Calibration should be carried out according to relevant national or international standards, after the equipment has been warmed up and stabilized, and the influence of ambient temperature and atmospheric pressure should be considered. Regular calibration helps maintain the measurement reliability of the device.
Influencing factors
The performance of a heated thermostatic circulation tank is affected by a variety of factors. The specific heat capacity, thermal conductivity and viscosity of the medium directly affect the heating rate, temperature uniformity and cycling efficiency. Environmental conditions such as ambient temperature, humidity and air circulation will affect the thermal insulation effect and heat loss of the tank. The characteristics of the equipment itself, including the matching degree between the heating power and the volume of the tank, the material and thickness of the insulation layer, the flow rate and head of the circulation pump, the response speed and installation position of the temperature sensor, and the parameter setting of the control algorithm, all have a direct impact on the accuracy and stability of temperature control. In addition, usage habits such as the heat capacity of the load, the length and diameter of the external circulation line, the cleanliness of the medium and the level of the liquid level also introduce variables in practical applications.
Applications:
Heating thermostatic circulation tanks are widely used in many scientific and industrial fields where precise temperature control is required. In the field of chemistry and chemical engineering, it provides a constant temperature heat source for chemical reactors, polymerization reactions, distillation and extraction, material synthesis, and other processes. In the field of analytical detection, it is used to maintain the constant temperature conditions of sample cells or components of analytical instruments such as spectrometers, refractometers, and viscometers. In the field of biotechnology (non-medical drugs), temperature control can be provided for fermentation research, enzymatic reactions, and cell culture-related equipment. In the field of physics and materials science, it is commonly used in experiments such as crystal growth, mechanical property testing of materials, and viscosity standard measurement. In addition, it also plays an important role in laboratories and pilot links in petrochemical, food engineering, environmental monitoring and other industries.
Selection considerations
When choosing a heating thermostatic circulation tank, it is necessary to consider many aspects. First, the temperature range requirements should be clarified to ensure that the maximum heating temperature and minimum starting temperature of the equipment meet the experimental requirements. Secondly, it is necessary to pay attention to the temperature control performance parameters, including temperature stability, uniformity and accuracy, which should match the allowable error of the experiment. The volume of the tank and the external circulation capacity are determined according to the size and quantity of the load and the pipeline resistance of the external circulation system. The choice of media type takes into account operating temperature, compatibility, and safety, such as silicone oil, water, or antifreeze. The functional characteristics of the equipment, such as whether it has a refrigeration function (becoming a constant temperature circulation tank), program heating/cooling, over-temperature protection, liquid level alarm, etc., should be evaluated according to the specific process requirements. Additionally, equipment reliability, ease of maintenance, energy consumption levels, and compatibility with existing laboratory facilities are also aspects worth paying attention to in the decision-making process.