Definition
High and low temperature stirring thermostatic chamber is a kind of laboratory equipment that integrates temperature control, fluid stirring and circulation functions. It provides a constant temperature liquid environment with precise temperature, uniform distribution, and dynamic control for the reaction vessel or external system through built-in heating and refrigeration systems, as well as stirring devices. Its operating temperature range usually spans from minus to minus 100 degrees, and is widely used in sample preparation, reaction process research and performance testing in materials, chemical industry, biology and other fields.
Principle
The core working principle of the equipment is based on closed-loop temperature control and forced convection heat transfer. The system is mainly composed of tank, heater, refrigeration unit, circulation pump, agitator, high-precision temperature sensor and controller. The controller receives the actual temperature signal feedback from the sensor, compares it with the target temperature value set by the user, calculates the control amount through the proportional-integral-differential algorithm, and dynamically adjusts the heater power or refrigeration unit output to achieve fast and stable temperature regulation. At the same time, the built-in agitator or circulation pump works continuously to promote the high-speed flow of thermal conductive media (such as silicone oil, water, ethanol, etc.) in the tank, effectively eliminating temperature gradients and ensuring a high degree of uniformity of temperature in the working area.
Measurement method
The evaluation of the performance of the high and low temperature stirring constant temperature tank is mainly carried out according to the methods specified in relevant national or international standards (such as JJF 1030-2010 "Technical Performance Test Specification for Constant Temperature Tank"). Measurements of key parameters include temperature stability, uniformity, and setpoint deviation. For measurement, multiple calibrated high-precision platinum resistance thermometers are placed in different spatial locations in the tank working area. After the set temperature point reaches a stable state, the temperature value of each temperature measurement point is continuously recorded. Temperature uniformity is characterized by calculating the maximum difference in temperature at each point at the same time. Temperature stability is assessed by calculating the maximum deviation of temperature fluctuations at a given point over a specific period of time. The setpoint deviation is the difference between the average measured temperature and the set temperature. These measurements are usually performed separately under no-load and typical load conditions.
Influencing factors
The actual performance of the equipment is affected by a variety of factors. Environmental conditions such as laboratory ambient temperature, humidity, and ventilation can affect the heat dissipation efficiency and temperature control stability of the refrigeration system. The selection of thermal conductive medium is crucial, and its specific heat capacity, thermal conductivity, viscosity and applicable temperature range are directly related to heat transfer efficiency and temperature field uniformity. Load characteristics, including the material, shape, heat capacity, and volume of the controlled sample or vessel, can alter the thermal inertia of the system, affecting the temperature response speed and stability. In addition, the installation level of the equipment, the rationality of the design of the circulating runner, and the setting of control parameters will also have a significant impact on the final performance.
Applications
As the basic temperature control equipment, the high and low temperature stirring constant temperature tank covers many scientific research and industrial testing fields. In the petrochemical industry, it is used for the determination of low-temperature freezing point and kinematic viscosity of lubricating oil, asphalt and other materials. In materials science, it is used for glass transition temperature research and thermal cycling testing of polymer materials and composite materials. In the field of electronics, it is used for environmental adaptability testing of components and circuit boards. In biotechnology, it provides a stable low-temperature environment for enzymatic reactions and cell culture. In addition, it is often used as a standard temperature source for calibrating measuring instruments such as temperature sensors and thermometers.
Selection considerations
Users need to consider comprehensively when choosing a high and low temperature stirring constant temperature tank. The primary parameters are the temperature range and temperature control accuracy, which should be determined according to the minimum temperature, maximum temperature and allowable temperature fluctuation range required by the experiment. The tank volume and opening size should be adapted to the commonly used experimental vessels, and sufficient media circulation space should be considered. The temperature uniformity index is related to the reproducibility of the experiment and needs to be paid attention to. The cooling mode of equipment (mechanical compression refrigeration, liquid nitrogen assisted refrigeration, etc.) determines its cooling speed and heat dissipation requirements at low temperatures. Circulation and agitation capacity, including pump flow and pressure, determines the effectiveness of the external equipment supply or tank mixing. Other factors to consider include user-friendliness, safety features (e.g., low level protection, over-temperature protection), compatibility of thermal media, and device size and power consumption. It is recommended to compare the technical parameters of different models on the premise of clarifying your own application scenarios and budget, and refer to relevant industry standards for selection.