Definition
Transparent refrigeration thermostatic tank is a commonly used temperature control equipment in laboratories, usually composed of transparent tank, refrigeration system, heating system, circulating stirring device and high-precision thermostat. Through the coordinated work of active cooling and heating, it can provide a stable and uniform temperature environment for the liquid medium in the tank in a wide temperature range, and realize the intuitive observation of the experimental process with the help of transparent materials. This equipment is widely used in sample constant temperature, viscosity testing, reaction incubation and other scenarios in materials, chemical, biology, metrology and other fields that require precise temperature control.
Principle
The core working principle of the transparent refrigeration thermostatic tank is based on closed-loop temperature control and fluid circulation heat transfer. The temperature sensor inside the device monitors the temperature of the medium in the tank in real time and feeds the signal back to the thermostat. According to the difference between the set temperature and the measured temperature, the thermostat calculates the control quantity through the proportional-integral-differential algorithm, and drives the refrigeration unit or heating unit to adjust the power. Refrigeration systems typically use compressor refrigeration or thermoelectric refrigeration technology to transfer heat from the tank to the external environment. The heating system replenishes heat with a resistive heating element. At the same time, the built-in circulation pump or agitator promotes the flow of the medium, reducing temperature stratification and ensuring the uniformity of the temperature in the tank space. The entire control process can be expressed as:
ΔT = Tset - Tactual
where ΔT is the temperature difference, TsetTo set the temperature, Tactualis the measured temperature. The controller output signal drives the actuator to bring the ΔT close to zero, so that it can achieve a constant temperature state.
Measurement method
The performance evaluation of transparent refrigeration thermostatic tanks should be based on relevant national or international standards, such as JJF 1030-2010 "Technical Performance Test Specification for Thermostatic Tanks". The main measurement parameters include temperature stability, uniformity, and fluctuation. Temperature stability refers to the degree to which the temperature of a certain point in the tank changes over time at a set temperature, usually by recording temperature data for a long time and calculating the standard deviation. Temperature uniformity refers to the temperature difference at different spatial points in the tank at a specific time, and multiple calibrated temperature probes should be arranged in the working area of the tank to record the temperature at each point and calculate the maximum deviation. Temperature fluctuation refers to the amplitude of periodic changes in temperature at a certain point in the trough in a short period of time, and the data can be collected and the peak and peak can be analyzed by a high-resolution temperature recorder. Use a traceable standard platinum resistance thermometer or thermocouple for measurements, and ensure that the measurement point is away from direct heating or cooling sources.
Influencing factors
The performance of a transparent refrigeration thermostatic tank is affected by a variety of factors. Environmental conditions such as laboratory ambient temperature, humidity, and ventilation can interfere with the thermal balance of the tank, which can lead to changes in refrigeration load or condensation. The choice of medium in the tank directly affects the heat transfer efficiency and temperature range, for example, silicone oil is suitable for higher temperatures, while water or ethanol aqueous solutions are often used near room temperature. The cooling and heating power configurations of the equipment need to match the target temperature range, as insufficient power will lead to slow heating or cooling, and excessive power may cause temperature overshoot. The tank insulation design, stirring cycle speed, and sensor placement also significantly affect temperature uniformity and response speed. In addition, the parameter setting of the control algorithm and the calibration status of the sensor are the key to ensuring long-term temperature control accuracy.
Applications
Transparent refrigeration thermostats have a wide range of uses in the fields of industry and scientific research. In materials science, it is used for the determination of glass transition temperature of polymer materials and the viscosity-temperature characteristic test of coatings. In the field of metrology, it serves as a constant temperature source for temperature sensor calibration. It is often used in the chemical industry for reactor jacket temperature control and crystallization process observation. The food industry can simulate product storage temperature conditions for stability testing. It is used in the electronics industry for testing the temperature characteristics of components. Its transparency is particularly suitable for teaching demonstrations, phase transition observations, and experimental processes that require visual monitoring, such as fluid dynamics visualization studies, biological sample culture observations, etc.
Selection considerations
When choosing a transparent refrigeration thermostatic tank, it is necessary to comprehensively consider the technical parameters and experimental needs. The temperature range should cover the minimum and maximum temperatures required for the experiment, with a certain margin. The tank volume should be adapted to the size and quantity of the sample, while paying attention to the depth and diameter of the effective working area. The temperature stability and uniformity indexes should meet the requirements of experimental accuracy, and the requirements of general basic research are high, while the process simulation can be appropriately relaxed. In terms of refrigeration method, compressor refrigeration is suitable for large temperature difference and low temperature demand, while thermoelectric refrigeration is suitable for small temperature difference and low noise scenarios. Safety features such as level protection, overheating protection, leakage protection, etc. should also be paid attention to. Interface scalability, such as external circulation interface, communication interface, etc., may affect the integration and use of the device with other instruments. Finally, consider energy consumption, ease of maintenance, and the supplier's technical support capabilities.