Definition
A low-temperature oscillating water bath is a lab equipment that integrates temperature control and oscillation to maintain a uniform and constant temperature of liquid media within a set temperature range and provide horizontal or cyclodynamic oscillation motion. Its typical operating temperature range typically covers the range of minus to tens of degrees Celsius, making it suitable for experimental processes that require sample mixing, reaction, or culture in low-temperature environments.
How it works:
The equipment is mainly composed of constant temperature tank, refrigeration system, heating system, oscillation mechanism and control system. The refrigeration system mostly adopts compressor refrigeration or thermoelectric refrigeration technology to reduce the temperature of the medium in the tank through heat exchange. The heating system is assisted in heating by electric heating elements, and the two work together to achieve precise temperature control. The oscillation mechanism is driven by a motor to generate periodic reciprocating or rotational motion of the sample container in the horizontal direction, promoting heat exchange and mixing between the sample and the medium. Based on the feedback of the temperature sensor, the control system uses PID algorithm to dynamically adjust the cooling and heating power, so that the temperature in the tank is stable at the set value.
Measurement method
Temperature measurement usually uses platinum resistance temperature sensors that comply with international standards (such as IEC 60751), and the relationship between resistance value and temperature can be approximately expressed as:Rt = R0[1 + A t + B t2 + C (t - 100) t3], among themRtis the temperaturetresistance value,R0nominal resistance at 0°C,A、B、Cis the calibration factor. Oscillation parameter measurements involve frequency and amplitude, which can be obtained by monitoring the motor speed with a photoelectric encoder or Hall sensor, and amplitude by a mechanical ruler or optical shift sensor.
Influencing factors
The temperature stability is affected by factors such as ambient temperature and humidity, heat capacity and fluidity of the medium, and the thermal insulation performance of the tank. The oscillation uniformity depends on the accuracy of the drive mechanism, the balance of load distribution and the fixing method of the container. In addition, the choice of medium, such as water, ethanol, or silicone oil, can change the heat transfer efficiency and the lower operating temperature limit. Fluctuations in power supply voltage may affect the operational stability of refrigeration compressors and oscillating motors.
Applications:
The equipment is used in material aging testing, chemical synthesis, environmental sample preparation, biological culture (non-medical field), food quality inspection and other scenarios. For example, it is used in environmental monitoring for water pollutant extraction, in polymer research for stress relaxation experiments at low temperatures, or in the food industry to simulate the mixing process of ingredients under refrigerated conditions.
Key points of selection
The selection should comprehensively consider the temperature range and fluctuation, oscillation frequency and amplitude range, tank volume and material, safety protection functions and energy efficiency standards. It is recommended to refer to international standards (such as ASTM E1157 specification for temperature calibration) and general technical indicators in the industry to determine the parameter matching degree according to the sample capacity, vessel type and experimental protocol requirements. Pay attention to verifying the temperature uniformity data of the equipment, the relationship between cooling power and cooling rate, and the operating noise and durability performance of the oscillating mechanism under different loads.