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Molten Salt Heat Exchange System vs. Traditional Heat Exchange System

Release time:

2025-04-18

Compared with traditional heat exchange systems (such as heat transfer oil, water/steam, air heat exchange, etc.), the molten salt heat exchange system (Molten Salt Heat Exchange) has significant advantages in high temperature conditions, energy storage capacity, safety and environmental protection, but there are also some challenges. The following is a detailed comparison:

1. Comparison of operating temperature range

System type	Typical operating temperature range	Applicable scenarios
Molten salt heat exchange system	220°C–800°C+	Solar thermal power generation, nuclear energy, ultra-high temperature industry
Thermal oil system	200°C–400°C (up to ~425°C)	Chemical, food processing, medium temperature heat storage
Water/steam system	100°C–350°C (high pressure steam)	Thermal power, traditional industrial boilers
Air heat exchange system	Normal temperature–1000°C (special materials required for high temperature resistance)	Metallurgy, gas turbine waste heat recovery

Molten salt advantages:

✅ Ultra-high temperature resistance (up to 800°C), suitable for high temperature scenarios such as solar thermal power generation and fourth-generation nuclear reactors.

✅ No phase change (traditional steam systems require latent heat of vaporization, and efficiency is limited).

2. Comparison of heat capacity and energy storage capacity

Parameters	Molten salt (Solar Salt)	Thermal oil (biphenyl/biphenyl ether)	Water/steam
Specific heat capacity (kJ/kg·K)	~1.5	~1.8	~4.2 (liquid water)
Energy storage density (MJ/m³)	800–1000	500–700	300–500 (sensible heat)
Is it suitable for heat storage?	Yes (large-scale heat storage)	Limited (easy to decompose)	High-pressure container required

Advantages of molten salt:

✅ High energy storage density: The heat storage capacity per unit volume far exceeds that of water/steam, which is suitable for long-term energy storage (such as 10+ hours of heat storage in a solar thermal power station).

✅ Low-cost heat storage: The price of molten salt is lower than that of organic thermal oil, and it can be recycled for a long time.

3. Comparison of safety and environmental protection

Characteristics	Molten salt system	Thermal oil system	Water/steam system
Flammability	Non-flammable	Flammable (fire prevention measures required)	Non-flammable
Toxicity	Low toxicity (nitrates)	Partially toxic (such as biphenyls)	Non-toxic
Environmental protection	No greenhouse gas emissions	May leak and contaminate soil	Non-polluting
Pressure requirements	Normal pressure/low pressure operation	Medium pressure (anti-boiling)	High pressure (steam system)

Advantages of molten salt:

✅ High safety: no combustion risk, suitable for high temperature industrial environment.

✅ Environmental protection: Molten salt (such as nitrates) can be recycled and has no carbon emissions.

4. Comparison of economic efficiency and maintenance cost

Factor	Molten salt system	Traditional system (heat transfer oil/steam)
Initial investment	High (high temperature resistant materials)	Low
Operating cost	Low (molten salt has long life)	Heat transfer oil needs to be replaced regularly
Maintenance difficulty	Antifreeze and corrosion protection are required	Heat transfer oil is prone to aging and coking

Advantages of molten salt:

✅ Better long-term economic efficiency: The life of molten salt can reach more than 20 years, and the heat transfer oil needs to be replaced every 3-5 years.

❌ High initial cost: due to the need for corrosion-resistant materials (such as stainless steel and nickel-based alloys).

5. Comparison of typical application scenarios

Scenario	Applicability of molten salt system	Applicability of traditional system
Concentrated thermal power generation (CSP)	★★★★★ (mainstream technology)	★★☆ (thermal oil temperature limit 400°C)
Nuclear energy (molten salt reactor)	★★★★★	Not applicable
Industrial waste heat recovery (>500°C)	★★★★☆	★★☆ (steam system pressure is too high)
Food/chemical (medium and low temperature)	★★☆ (overheated)	★★★★★ (thermal oil/steam)

Advantage scenarios of molten salt:

✅ High-temperature industry (such as steel and glass manufacturing).

✅ Renewable energy storage (concentrated thermal power station with heat storage).

6. Challenges of molten salt system

Although the molten salt heat exchange system has many advantages, it also has the following problems:

6.1.High anti-solidification requirements: Molten salt has a high solidification point (such as solar salt ~220°C), and requires continuous insulation or electric heating.

6.2.Material corrosion: Metals may corrode under long-term high temperatures, so corrosion-resistant alloys (such as Inconel) need to be selected.

6.3.System complexity: Storage tanks, high-temperature pumps, and anti-condensation measures are required, and installation and maintenance are difficult.

7.Summary: Core advantages of molten salt systems

Comparison dimensions	Molten salt system	Traditional system
High temperature resistance	✔️ Far beyond the limit	❌ Limited
Energy storage capacity	✔️ Large capacity	❌ Limited
Safety	✔️ Non-flammable	❌ Partially flammable
Environmental protection	✔️ No pollution	❌ Possible leakage
Long-term economic	✔️ Low maintenance	❌ Medium replacement required

Applicable selection suggestions:

7.1.Ultra-high temperature (>400°C), scenarios requiring heat storage (such as solar thermal power generation) → Molten salt is preferred.

7.2.Medium and low temperature (<400°C), low-cost requirements → Thermal oil or steam systems are more suitable.

Molten salt heat exchange system is a revolutionary technology in the field of high-temperature energy, especially suitable for clean energy storage and efficient utilization in the future carbon neutrality background!

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