Updates and iterations of refrigerator insulation materials

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From the first generation of products with heavy appearance and amazing energy consumption to modern household appliances with high efficiency, beauty and environmental protection, the core driving force of each transformation of the freezer comes from the iteration and innovation of insulation materials. This article will trace the evolution of three generations of materials from glass wool, polyurethane foam to vacuum insulation panels, and show how material science can reshape the freezer step by step from an ice box that meets the basic storage function to a smart life companion that combines design aesthetics and excellent energy efficiency.

(1)、Glass wool

In the 50-70 s of last century, glass wool was the mainstream insulation material. Early horizontal freezers were usually filled with glass wool in the cavity between the freezer shell and the inner container.

1. material advantages

①. The freezer compressor generates heat when it works, and the non-combustible nature of glass wool provides safety.

②. The low cost is suitable for the large-scale popularization of household refrigerators at that time.

2. obvious Defects:

①. Easily hygroscopic and icing

The low temperature environment inside the freezer makes the box body easy to frost, moisture will gradually invade the insulation layer, and the insulation performance of glass wool will drop sharply after moisture absorption.

②. amazing thickness

In order to achieve the basic insulation effect, the wall thickness of the early freezer can reach 10-15cm, and the appearance is bulky.

③. Cold bridge problem

The filling is not tight to form a heat flow channel, resulting in serious local frosting.

The power consumption of the glass wool freezer is extremely high, the daily power consumption is often more than 2 degrees, and the effective floor area ratio is low, which has given birth to the industry's pursuit of more efficient and friendly materials.

(2)、Polyurethane foam

After the 1970 s, polyurethane rigid foam completely changed the freezer manufacturing through on-site foaming technology: the mixed liquid raw materials were injected into the interlayer of the freezer shell and the inner container, and expanded and solidified within a few minutes to form a seamless insulation layer completely consistent with the shape of the box.

1. revolutionary Progress

①. structural integration

After curing, polyurethane foam has strength, can connect the shell and the inner tank to a certain extent, enhance the box structure, and can completely fill every corner, eliminating the "cold bridge".

②. Thermal insulation performance improvement

The thermal conductivity is reduced to 0.022-0.028W/(m · K), and the thermal insulation

capacity is significantly enhanced.

③. Excellent moisture resistance:

The obturator rate exceeds 90%, effectively blocking water vapor penetration and avoiding performance attenuation caused by moisture absorption of the insulation layer.

④. Increased production efficiency:

Suitable for assembly line production, the foaming and curing of a freezer can be completed within 10 minutes, which promotes the large-scale popularization and price reduction of freezers.

2. insurmountable Limitations

Despite being the gold standard, the physical limits of polyurethane foaming constrain the further evolution of freezers:

①. thermal conductivity bottleneck

Even the best quality polyurethane foam, its thermal conductivity is difficult to lower than 0.022W/(m · K), which means that to achieve the desired insulation effect, the material thickness must be increased, taking up valuable product space.

②. Long-term performance decay

The foaming agent in the foam will gradually diffuse away and be replaced by air, resulting in a decrease in thermal insulation performance of about 10%-20% over time.

③. Environmental challenges

The early use of HCFC blowing agents has a destructive effect on the ozone layer. Although it has been gradually eliminated, it is still a challenge to find a completely environmentally friendly and efficient alternative.

These limitations are driving the next revolution in insulation.

(3)、Vacuum insulation panel (VIP)

Vacuum Insulation Panel (VIP) represents the current commercial top insulation materials. The basic principle draws on the design concept of the thermos: to create a high vacuum environment in the closed plate structure, to minimize the heat conduction and convection caused by gas molecules.

1.VIP's three core technology breakthroughs:

①. Porous core structure

The VIP is filled with micron-sized porous materials, such as fumed silica, glass fiber or open-cell polyurethane foam. These materials create a network of nanoscale pores that drastically reduce conduction and radiative heat transfer in solids. The porosity of the fumed silica core material is as high as more than 90%, and the average pore size is only about 100 nanometers, which is smaller than the mean free path of air molecules, which greatly inhibits the heat conduction of the gas.

②. Extreme vacuum environment

The VIP interior is pumped to a high vacuum state of 0.1-1 Pa, which is more than 1000 times higher than the vacuum in the ordinary thermos. In this environment, the thermal conduction of the residual gas molecules is almost negligible.

③. High barrier packaging technology

VIP is encapsulated in multilayer aluminum-plastic composite film or metal sheet, and its water and oxygen permeability is extremely low (usually <0.005g/m² · day), ensuring that a high vacuum is maintained during the service life of 15-20 years.

2. data comparison:

①. The thermal conductivity of VIP can reach 0.002-0.005W/(m · K), which is 5-10 times lower than that of polyurethane foam

②. Under the same insulation effect, the thickness is only 1/5-1/10 of traditional materials

③. Stable performance in the -40°C to 90°C range.

(4)、Optimization of new materials for freezer volume and energy efficiency

The application of VIP technology has brought revolutionary changes to the design of the freezer, realizing the dual optimization of volume and energy efficiency:

1. volume optimization

①. Wall thickness reduction

The thickness of the traditional refrigerator insulation layer usually needs 40-80mm, while VIP only needs 10-20mm to achieve the same or better insulation effect.

②. Volume increase

In the case of the same external dimensions, the use of VIP can increase the effective volume of the freezer by 15-30%.

③. Freedom of Design

The ultra-thin features allow designers to create slimmer, beautiful product forms that break through the bulky image of traditional freezers.

2. energy efficiency optimization

①. Energy consumption reduction

The refrigerator with VIP can save 20-40% energy than the traditional model, and some high-end products can save more than 50% energy.

②. temperature uniformity

VIP's excellent thermal insulation performance makes the temperature distribution in the cabinet more uniform, reduces the local temperature difference, and is conducive to food preservation.

③. Fast Recovery

After opening the door, the temperature recovery time is shortened by 30-50%, reducing the frequent start and stop of the compressor.

④. Contribution to environmental protection

Reduce electricity consumption and thus indirectly reduce carbon emissions, while the VIP itself does not contain harmful blowing agents.

Conclusion

In the era of glass wool, freezers are bulky containers that meet basic storage functions. The popularity of polyurethane foam has made it popular and become standard for families. The maturity of vacuum insulation technology has led freezers into a new era of large volume, ultra-low energy consumption and elegant design. With the continuous optimization of thermal insulation material performance and the continuous improvement of environmental protection requirements, the future freezer will be more intelligent, more integrated, closer to the essence of sustainable life, continue to guard the fresh in the quiet, to create greater value with less resource consumption.