How does a constant-temperature cup achieve "constant temperature"? Understand its working principle in one article

When you want to have a sip of warm water at any time in the cold winter, or when preparing milk for your baby, you don't have to rush to test the temperature. The appearance of the stainless steel constant temperature cup has perfectly solved these pain points. But it neither simply "keeps warm" like a thermos nor continuously "heats up" like an electric kettle. How does it miraculously achieve "constant temperature"?

In fact, the constant temperature cups available on the market are mainly divided into two technical schools: phase change material constant temperature cups and electric heating constant temperature cups. The principles they implement are completely different.

I. Phase Change Material Constant Temperature Cup (Mainstream and Common)

This is the most common type of thermostatic cup we see. It doesn't need to be plugged in or charged. The core secret lies in a special Material filled between the inner liner and the outer shell - Phase Change Material (PCM).

1. Core principle: Phase change heat storage

Phase change materials can undergo physical state changes (such as from solid to liquid) at specific temperatures. This process absorbs or releases a large amount of energy (latent heat), while the temperature itself remains relatively constant.

Common phase change materials: Usually a carefully formulated pure wax-based mixture (Food-Grade Wax), with its phase change temperature precisely set at around 55°C (which is also the most suitable temperature for drinking).

2. Work Process Decomposition:

Step 1: Pour in hot water to store energy

When you pour boiling water (90-100°C) into the cup, the high-temperature hot water will transfer heat to the phase change material through the stainless steel inner liner.

When the temperature of the phase change material reaches its melting point (for example, 55°C), it will start to melt and change from solid to liquid. This melting process absorbs and stores a large amount of heat in the water, thereby rapidly and significantly lowering the temperature of the boiling water to a range suitable for drinking.

Step 2: Maintain a constant temperature and release energy

When you start drinking, the water temperature in the cup will gradually drop due to the environment.

When the water temperature drops to the freezing point of the phase change material (for example, 55°C), the previously melted liquid phase change material will start to solidify and return from liquid to solid. This solidification process will release the heat it previously stored, compensating for the heat lost by the cup, thereby maintaining the water temperature at around 55°C for a long time.

It can be understood as a "thermal energy battery" :

Charging: Pour in hot water, the material melts, and heat is stored.

Discharge: Water temperature drops, material solidifies, and heat is released.

Advantages: Safe, no need for electricity, long service life (the material will not fail).

Disadvantage: The constant temperature is fixed and cannot be adjusted. In the initial stage, enough hot water needs to be poured in to activate it. The heat preservation time is not as long as that of top-grade vacuum insulated cups.

Ii. Electric Heating Constant Temperature Cup (Intelligent Active Type)

This type of thermostatic cup is more like a portable mini electric kettle, which works actively through electricity.

1. Core components

Built-in battery: Provides power.

Heating plate/heating film: Wrapped around the bottom or periphery of the inner tank, it is used for heating.

Temperature control sensor: Real-time monitoring of water temperature.

Control circuit board: The brain, processes sensor signals and controls the heating switch.

Display panel: Shows real-time water temperature, set temperature, etc.

2. Working process

Users can set a desired temperature (such as 40°C, 55°C, or 90°C) by pressing a button.

The control chip monitors the water temperature in real time through the temperature control sensor.

When the water temperature is lower than the set temperature, the circuit board connects the power supply and the heating plate starts to work, heating the water in the cup.

When the water temperature reaches or exceeds the set temperature, the circuit board cuts off the power supply and stops heating.

This cycle repeats itself, and through the closed-loop control of "heating - stopping - heating - stopping", the water temperature is precisely maintained within a very small fluctuation range.

Advantages: The temperature can be precisely set and adjusted, with more functions (such as APP control and timing), and extremely strong heat preservation effect.

Disadvantages: Regular charging is required, the structure is complex and the cost is high, and there is a certain risk of circuit safety (products with protection functions such as anti-dry burning should be selected).

Summary and Comparison

Purchase Tips

Identify the type: Before purchasing, make sure to distinguish whether it is a phase change type or an electric heating type, as this determines whether you need to charge it.

Make sure to choose the material: The inner tank must be made of 304 or 316 medical-grade stainless steel to ensure safety and harmlessness.

Select as needed

If you only want your child or yourself to have warm water to drink at any time, the phase change material cup is economical and practical.

If you are a business person who travels frequently or like to drink tea or coffee at a specific temperature, an electric heating cup is more suitable.

I hope this article can help you thoroughly understand the "black technology" in the constant temperature cup!