In a month, 1 asic uses 1 mW of energy. At the same time, 150 kW of it is spent on the work of fans: 1500 rubles out of every 10 thousand. The immersion method will reduce these costs. Without experience in the assembly of cooling baths, it is difficult to choose which immersion liquid for mining will suit better. It is important to understand how the process is carried out.
A household example of immersion cooling. A heated spoon dipped in ice cream will cool down. The dessert will act as a heat transfer medium, taking away the temperature difference and releasing the resulting energy in the form of melting.
Immersion cooling is the immersion of appliances in a heat transfer compound to reduce the temperature.
Most often water is used to cool objects, but not electronics. For equipment, this liquid is not suitable due to its high electrical conductivity. The experience will end with a short circuit in one of the transistors. The device cannot be restored.
Dielectrics are compositions that do not conduct energy. Such solutions can be used for immersion cooling of equipment. Because of this property immersion liquids are called “dry water”.
Comparison of immersion cooling with air cooling
Manufacturers install ventilation in the enclosures of 95% of devices, the disadvantages of which are noise and high energy costs. The immersion method has several differences when comparing it to air cooling:
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- Low noise figure. The liquid method reduces its level from 80 dB to 50 dB – this is the volume of clear conversational speech.
- Protection from indirect factors of overheating – dust and moisture ingress. This will prolong the operation of the equipment.
- Space saving. You can install miners tightly to each other. For example, the bath for 18 asics takes 1.6 m2.
- Environmental friendliness. Built-in fans consume 15% of the energy resources of the device. The cost of ASIC without air system is 30% lower.
- Stable temperature allows you to overclock the device without the risk of overheating by 30%.
Disadvantages of the method:
- Overconsumption of coolant in case of improperly designed bath.
- High cost of compositions leading in the characteristics of heat capacity and environmental friendliness.
- The need to modify the equipment and assemble a special tank.
- The need to combine with air and/or water cooling.
- Low combustion temperature of budget dielectric types.
- Termination of warranty service conditions.
Types of immersion cooling
To assess the risks and choose an immersion liquid for mining, it is important to understand the features of the compositions. Not all coolants are safe for health and computer equipment.
Dielectric properties are not the only thing that should be considered when choosing.
Coolants come in single-phase and two-phase. In both cases, the dielectric accepts temperature, but it also needs cooling to cool down. Immersion baths must therefore be supplemented with an external air fan or water condensers.
For single-phase designs, a piping system and a pump to control the flow must be installed. It is also important to provide air cooling outside the bath.
Two-phase fluids work on a different principle. The first part consists of heating to 61°C and boiling. The second is evaporation and condensation. As in the case of melting ice cream, the refrigerant is partially cooled down due to the volatility property and also with the help of water.
If the immersion bath is not closed, vaporization will take place into the atmosphere. Therefore, sealed systems with a condenser must be modeled to use two-phase coolants. The external tank is filled with water using the flow-through method. It is also possible to cool the structure with an air fan. The dielectric solution remains in the closed circuit at all times. The boiling and condensation cycle is endlessly repeated.
For two-phase dielectrics, high volatility is an advantage. For single-phase dielectrics, it is a disadvantage: the index must be low.
Properties of immersion fluid for mining
Regardless of the presence or absence of a phase transition, immersion fluids are selected according to the same characteristics:
- Heat capacity of the refrigerant.
- Toxicity when inhaled or in contact with the skin.
- Effect on farm components with which the solution will interact.
- Hygroscopicity.
- Vaporizability (volatility).
- Burning temperature.
- Price.
There are 5 types of dielectrics. Only three of them are suitable as immersion liquid for cooling asics.
| Type of coolant | Type | Cost | Used in mining | Comment |
|---|---|---|---|---|
| Low value of thermal conductivity when the threshold of 60°C is reached. Components are similar to hydraulic lubricants. Burns from 170°C to 200°C. Odorless. | ||||
| Good thermal conductivity characteristics. Burning threshold from 256°C. For some budget brands it is lower – from 128°C. Otherwise safe, non-hygroscopic, odorless. | ||||
| Has thermal conductivity and dielectric properties at a sufficient level for computer components. On the downside: toxic vapors. The substance destroys electronics components, absorbs moisture from the air, has a strong unpleasant odor. | ||||
| High thermal conductivity. Purified solutions should be selected. Used in cosmetic products. Not toxic, does not evaporate, not hygroscopic. | ||||
| Increased heat transfer values. Volatility at 61°C. Not flammable. Not toxic. Does not contaminate the environment. The solution is also used to put out electronics fires. |
How to choose an asics cooling liquid
Immersion cooling of miners is effective when using both single-phase and two-phase types of solutions. In the first case, it is better to choose a liquid based on mineral or synthetic oils. Silicone compositions can be used. However, it is necessary to choose brands with a high temperature of ignition.
From the minuses of the system:
- The size of the installation is larger than that of baths for two-phase compositions.
- The need to supplement with remote ventilation. This adds noise during operation. Energy consumption is also increased.
- Risk of encountering a composition that is not safe for health or equipment.
- Likelihood of liquid spills. Difficulties in cleanup.
- The temperature of ignition is high. However, if the limit values are reached, the fire cannot be extinguished without special means.
- Constant volume control. It is necessary to refill the composition.
From the pluses of the system:
- The cost of solutions is 17 times less.
- Simplicity of assembly. The bath is not difficult to construct, often aquariums are used for this purpose.
- Profitability for small farms and single asics.
Two-phase fluids require a different farm design. Tanks are modeled taking into account more than 20 technological nuances. These include leak tightness, pressure build-up compensation, thermal resistance of heat sinks, materials of heat exchange components, etc.
Of the disadvantages:
- Engineering complexity of the bath.
- Large cold water consumption for the flow condenser. Baths for 8 asics will require 0.6 m3/h. Tanks for 18 devices will require 1.3 m3/h.
- High price.
- Difficulty of acquisition. Often the waiting period for delivery is several months.
- Unprofitable for mining on a single farm of 8 cards.
Advantages:
- Compact size.
- Less noise.
- Because of the closed circuit, you do not need to regularly buy and refill the coolant.
- Use of environmentally friendly compounds.
The most common brands of immersion liquids for mining are Novec, Bluemead, Coolant.
Novec
The Novec brand is manufactured by 3M. The corporation has been dealing with antifreezes since the 1950s, when coolants were created for aviation tasks. The solutions are chosen by the Intel technological concern for its servers. For the last 25 years the manufacturer has been innovating in cooling computer equipment. Technical fluids are produced both with and without phase transition.
Single-phase compositions: Novec 7300 and 7500. Two-phase – Novec 7000, 7100 and 7200.
The main advantage of phase transition coolants is the intentionally reduced boiling point to the level acceptable for computer chips (61°C). Before immersion in the immersion bath, it is important to remove thermal paste from the board elements and replace it with copper plates.
Main features:
- Does not cause corrosion of electronics.
- Non-flammable.
- Low viscosity solution.
- Colorless and odorless.
- High heat transfer coefficient.
- Does not require stirring. This function is performed by the boiling process.
- In gaseous form it is safe for inhalation.
- Cost from 10 000 rub/kg.
For single-phase systems, Novec solutions have a high boiling point of 120°C. Dielectrics produced by 3M are used not only as refrigerants. The same compositions can be used to clean contaminants from lubricants. For example, to remove traces of silicone oil. It is also used to extinguish high-temperature fires from 200°C.
Blumead
Beeminer manufactures ready-to-use immersion baths and produces a solution called Blumead. The liquid contains a single-phase dielectric PMS-50, which is a silicone oil.
Characteristics of Blumead refrigerant:
- Burning temperature 285°C.
- Color blue.
- Odorless.
- Non-hygroscopic.
- Does not vaporize.
- Does not cause corrosion of equipment.
- Safe in contact with skin.
- Cost on average 1000 rubles/liter.
Analog of Blumead is any solution of PMS-50. Approximate price of silicone oils – from 600 rubles/liter.
Coolant
Coolant dielectric is produced by the Polish company BiXBiT. According to the information on the official website, the substance is a “non-polymerizing” single-phase liquid. Mineral oils are used in the base. Exact information about the composition is not provided. Main characteristics:
- Odorless.
- Safe for humans and animals.
- Burning temperature 225°C.
- Cost from 220 rubles/liter.
There are not so many manufacturers of immersion liquids. However, it is recommended to critically assess the integrity of each before purchase. This will help to avoid pointless costs or damage to equipment.
What you need to pay attention to when choosing a seller:
- An intelligible composition of the liquid is specified.
- Prices and delivery dates are spelled out.
- Combustion, safety, heat capacity, viscosity, etc. are listed.
- Safety certificates for the solutions are provided.
It is important to be sure to double-check the listed data. They must be suitable for the components of the solution.
Rules of use
Rules that are important to consider when using immersion cooling:
- Use safe formulations.
- Remove the air ventilation system before immersion. Also remove layers of thermal paste that slow down heat transfer.
- Do not allow water to leak into the cooling solution.
- For single-phase formulations, ensure mixing.
- Monitor the fill level.
Liquid cooling reduces electricity consumption by 15%. In combination with stable temperature, it increases hash rate by a third. No less important is the resulting comfort from working with quiet mining equipment.
Frequent questions from users
📣 What is the difference between immersion cooling and waterblock?
In the first case, the equipment is lowered into a dielectric liquid. In the second case, the cooling is carried out by piping the substance to certain parts of the device.
🔥 Does the immersion unit raise the performance of the asic?
No. However, stable temperature allows overclocking with traditional tools – software or command line arguments.
📢 Which is better: to assemble a bathtub yourself or buy a ready-made one?
With a single-phase system, the design can be done yourself. However, it is safer to buy a ready-made system. The design of a biphasic cooling bath is very difficult to model.
✨ How regularly should the thermal paste be changed?
Replacement is recommended once every six months.
📌 What is the advantage of water cooling?
It can reduce the average temperature by 10-15%. It is worth considering the profitability of the farm to make the purchase of additional equipment pay off.
⚡ Can a card overheat with immersion cooling?
This is possible if the heat exchange is impaired. Causes may be pump malfunction, clogging in the supply pipes, insufficient dielectric movement, etc.
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Author: Saifedean Ammous, an expert in cryptocurrency economics.
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