Plus range heating storage tank with tubular exchanger 500 litres

Role of the serpentine shell-and-tube heat exchanger

The tubular heat exchanger, located at the bottom of the storage tank, is a spiral-wound tube (coil) through which a hot heat transfer fluid (e.g. solar fluid, boiler water, etc.) circulates. This coil heats the water in the cylinder by indirect heat exchange.

Advantages :

• Optimized heat transfer: the serpentine shape increases the exchange surface area, which improves thermal efficiency.
• Separation of circuits: fluids do not mix. The heat exchanger remains a closed circuit, ideal for systems with antifreeze or pressurized fluids (solar, wood boilers, etc.).
• Safety and versatility: it makes it easy to connect one or more energy sources (such as a solar panel and a boiler), while complying with safety standards.

Coil features :

Range with heat exchanger in lower part Exchangeable thermal capacities are given either in Kw or in kcal/h, depending on the average temperature difference between primary and secondary, all calculated according to a flow rate of 3m3/h.
For example, on a 1000-liter storage tank, with a primary inlet at 80°C and an outlet at 70°C, considering an average storage temperature of 60°C :
The average temperature difference is: (80 + 70) / 2 - 60 = 15°C
The graph shows that approximately 32 Kw can be exchanged.

Optimized thermal stratification thanks to deflectors

Stratification is particularly effective thanks to deflectors positioned on the inlets, which deflect the flow by making the inlet less direct and more diffuse, avoiding turbulence and mixing that disrupt thermal stratification
Sampling crosses allow water to be drawn from the highest, and therefore hottest, points.

In a nutshell:

Thermal stratification is essential in a storage tank, as it enables layers of water to be maintained at different temperatures without mixing.

This optimizes the use of stored energy: the hottest water remains available at the top of the tank for immediate needs (such as heating or domestic hot water), while the coldest water remains at the bottom, ready to be reheated.

Here's why baffles play an important role:

• Reducing turbulence: Without a deflector, water entering the tank creates a direct jet that disrupts the established thermal layers. Turbulence leads to temperature mixing, which reduces system efficiency.
• Diffused water entry: Deflectors direct and slow the incoming flow, allowing the water to gradually integrate into the equivalent temperature layer. This preserves stratification.
• Greater energy efficiency: Good stratification means that heat is used where it's needed, reducing energy consumption to heat the entire body of water unnecessarily.

In short, deflectors increase overall storage tank performance by enabling intelligent thermal storage, with fewer losses and greater system responsiveness.