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Battery Liquid Cooling System Overview

Background of battery liquid cooling system development

At the early stage of the development of new energy vehicles, new energy manufacturers continued the design ideas of fuel vehicles for the manufacturing of electric vehicles, but at this time, the motor, battery and charging heat power is low, so the industry generally adopts passive heat dissipation for battery thermal management, of which the more representative ways are air flow and heat sink passive heat dissipation.

Battery Liquid Cooling System Overview-EV BATTERY PACK THERMAL MANAGEMENT

With the rapid innovation of motors, supercharging, fast charging and other related technologies, the thermal management technology of batteries is facing a huge challenge. The passive heat dissipation method represented by air cooling can no longer meet the new demand of battery heat dissipation, so liquid cooling technology as a more effective active heat dissipation method instead of the previous passive side of the heat dissipation method.

Liquid cooling technology can provide stronger heat dissipation efficiency and uniform temperature distribution through liquid cooling circulation system to ensure the performance of the battery and the number of cycles. Trumonytechs, a thermal management specialist with extensive design and manufacturing experience in the thermal management industry, can provide products and designs related to not only liquid cooling of power batteries, but also energy storage systems, high heat flow density applications and new liquid cooling heat transfer technologies.

Application of liquid cooling system in the industry

There are four main applications of battery liquid cooling system, which are power battery field, energy storage field, high heat flow density field and new liquid cooling heat exchange components.

In the field of electric vehicles, the design of thermal management is more complex than that of fuel vehicles due to the increase of the three electric systems, in which the cooling performance of the power battery is the core of thermal management design, and the cooling performance will directly affect the efficiency and performance of new energy vehicles.

The lithium battery commonly used in power batteries is the power source of the vehicle, which is connected in series and parallel to form a battery moduleDuring the electrochemical reaction of the lithium battery, it is very sensitive to temperature changes, and generally needs to be kept at 15℃~35℃, too high or too low will affect the safety and performance.

The liquid cooling system has unique advantages in meeting the working temperature requirements of the power battery between the two circuits of cooling and heating. Compared with air cooling, liquid cooling also has the characteristics of large heat carrying capacity, low flow resistance and high heat transfer efficiency. With the increasing energy density and faster charging and discharging speed, liquid cooling is becoming the first choice of mainstream new energy vehicle manufacturers.

Components of the battery liquid cooling system

The liquid cooling system of the battery is composed of the following components:

1. Liquid cooling plate: This component is the core component of thermal management and is usually made of materials with good thermal conductivity, commonly made of aluminum and copper. The heat dissipation components are installed on the surface of the water-cooled plate, and the heat is absorbed by the coolant passing through the internal flow channel of the water-cooled plate to dissipate heat.

2. Liquid cooling circulation system: including cooling channels, electric pumps, circulation path of cooling liquid and other related components.

3. Cooling fluid: the common term is heat transfer fluid, used in a way that the heat of the parts to be dissipated is conducted to other systems, and this fluid plays the role of a heat transfer medium in the process of heat dissipation.

4. Control system: Usually consists of temperature sensors, control units and actuators to detect and control the temperature of the battery so that the temperature of the battery is within a safe range.

5. Cooling fan: The cooling component carries away most of the heat through the circulating flowing coolant in the flow channel, and the remaining residual heat is discharged to the outside through the fan.

Cooling fluid selection

Coolant generally refers to the fluid that surrounds or flows through a system used for heat transfer. The ideal coolant generally has the characteristics of high heat capacity, low viscosity, cheap, non-toxic, chemically inert, non-corrosive and insulating, and the following will focus on the characteristics of various coolants.

Water: Water is a good heat dissipation medium with good thermal conductivity and heat capacity, but water is a non-insulating fluid, so it is commonly used in non-direct contact type of liquid cooling technology.

Water/glycol mixture: A mixture obtained by mixing water with glycol, which has a high boiling point and anti-freeze properties and can be used to improve the performance of coolants.

Mineral oil: It has good thermal conductivity, lubrication performance and stability, and is also relatively inexpensive, but it is not suitable for heat dissipation in high temperature environments and has the risk of combustion.

Fluorinated fluids: initially used for circuit board cleaning, its main components are fluorinated organic compounds, with low toxicity, high electrical insulation, excellent thermal stability and chemical inertness, etc., and now used in large-scale submerged cooling.

When selecting various coolants, the final decision needs to be made by considering the temperature range of the application, heat transfer requirements, corrosiveness, environmental friendliness, and cost.

For more information, see the article: What Is The Best Liquid For Cooling?

Principle of liquid cooling system

The basic principle of liquid cooling system for new energy vehicles is to ensure the performance and reliability of each component by circulating coolant to absorb heat from the heat dissipation components and maintain them within the appropriate temperature range.

The system consists of components such as expansion kettles, condensers, cooling fans, electronic water pumps, three-way solenoid valves and battery liquid cooling tubes. In the system, the coolant serves the function of heat exchange to the battery cells. When cooling is required, the coolant flows into the condenser and takes away the heat by the action of the crash air. Then it enters the electronic water pump for pressurization, and the coolant enters the electric control and electric drive system for heat exchange, and flows to the battery pack or condenser through the control of the three-way solenoid valve.

Compared with air-cooled cooling, the technical advantages of liquid-cooled cooling are more obvious, and the cooling efficiency and balance are better. tronytechs is an expert in thermal management industry, and we provide thermal management solutions for customers at home and abroad all year round, not only providing technical support, but also serving your needs from prototype to production.