High-performance vacuum thermosiphon with phase-bound two-pipe guidance for thermal reheating and monovalent energy supply of heat pumps

Abstract

High-performance vacuum thermosiphon with phase-bound two-pipe routing for thermal reheating and monovalent energy supply of heat pumps (10) for thermal reheating and energy supply of heat pumps, comprising a closed pipe system with a riser pipe (11) for the vapor phase and a spatially separated return pipe (12) for the liquid phase, which are connected to each other at the lower end via a probe foot (13) and at the upper end via a heat exchanger (15), characterized in that a siphon element (14) is arranged in the return pipe (12) immediately downstream of the heat exchanger (15), which acts as a physical vapor barrier and forces a directed vapor flow exclusively in the riser pipe (11).

Description

Technical field:

[0001] The invention relates to a geothermal system for extracting heat energy from the subsurface, in particular from groundwater-bearing layers, using the thermosiphon principle (heat pipe). The device serves to increase the efficiency of water-brine heat pumps by targeted thermal reheating of a primary circuit or as a monovalent heat source. • Background of the invention (state of the art): Conventional geothermal probes or flat-plate collectors often suffer from thermal exhaustion in winter, which causes the source temperature to drop and reduces the efficiency (COP) of the heat pump. Existing thermosiphon systems often reach the "entrainment limit" at high outputs, where rising steam and descending condensate collide in the same pipe, making heat transfer unstable.

[0002] The technical problem The invention is based on the objective of creating a maintenance-free, passive system that stably transfers high thermal power from shallow depths (approx. 12 m) without the disadvantages of conventional well systems (iron fouling, pump current) or the performance limits of classic heat pipes. Disclosure of the invention (The solution)

[0003] The task is solved by a vacuum two-pipe system that simulates a consistent spatial separation of the phases. 1. Phase separation: The device consists of an ascending steam pipe (11, preferably a 54 mm copper pipe) and a spatially separate descending condensate branch (12, preferably a 42 mm copper pipe). These two pipe sections are connected at the lower end, the probe foot (13), via a bonded U-connection to form a completely closed circuit. 2. Vapor barrier (siphon): The key innovation is the integration of a siphon (14) in the return line, which is positioned immediately after the outlet of the heat exchanger (15). This liquid column acts as a physical barrier, preventing vapor flow in the return pipe (12) right at the transition from the condenser. This forces a directed vapor flow in the main pipe (11), eliminating the entrainment limit and stabilizing the pressure-relieved zone (19) throughout the entire further course of the return pipe. 3. Pressure-relieved zone: Due to the geometric arrangement of the siphon, a pressure-relieved zone (19) is created in the descending condensate branch as a gas space. This enables a pressure-neutral transition of the liquid working medium from the siphon to the lower probe area and prevents the build-up of a restrictive back pressure in the return line. 4. Single-phase condensation: The spatial separation of the pipes and the targeted heat extraction at the heat exchanger (15) ensure that only the liquid phase is present in the return pipe. Re-evaporation of the condensate is effectively prevented, which stabilizes the continuous heat flow. 5. Modularity: The system is designed to be integrated either as a post-heating stage into the return flow of a flat-plate collector (hybrid operation) or to enable a monovalent full supply by keeping several probes in parallel (cascade). 6. Vacuum Operation: The system operates under high vacuum with an alcohol-based working fluid (ethanol), which enables boiling to begin even at low groundwater temperatures (approx. 8-10 °C) or lower. The pressure-relieved zone (19) and consistent phase separation ensure stable operation of the thermosiphon even with decreasing source temperatures in the depths of winter. Advantages of the invention: • Maintenance-free: Hermetically sealed system without moving parts for lifetime operation. • Passive: High-performance energy transport without any auxiliary energy (0-watt primary power). • Highly efficient: Significant increase in the source temperature for heat pumps to achieve seasonal performance factors (SPF) > 5.0. • Environmentally friendly: Operation with biodegradable working medium (ethanol) without water extraction from the ground. • High performance: Transfer of high thermal power even from shallow depths (approx. 12 m) Reference symbol list 10 High-performance vacuum thermosiphons 11 Riser pipe (vapor phase) 12 Return pipe (liquid phase) 13 Probe foot material-bonded U-connection (evaporator) 14 Siphon element (steam stop) 15 heat exchangers (condensers) 16 Vacuum connection (sealed) 17 Heat source (soil / groundwater) 18 Working medium (ethanol) 19 Pressure-relieved zone (gas space)

Claims

[1] High-performance vacuum thermosiphon with phase-bound two-pipe guidance for thermal reheating and monovalent energy supply of heat pumps (10) for thermal reheating and energy supply of heat pumps, comprising a closed pipe system with a riser pipe (11) for the vapor phase and a spatially separated return pipe (12) for the liquid phase, which are connected at the lower end via a probe foot (13) and at the upper end via a heat exchanger (15), characterized by , that in the return pipe (12) immediately downstream behind the heat exchanger (15) a siphon element (14) is arranged, which acts as a physical vapor barrier and forces a directed vapor flow exclusively in the riser pipe (11). [2] Thermosiphon according to claim 1, characterized by, that the geometric arrangement of the siphon element (14) in the descending return pipe (12) creates a pressure-relieved zone (19) as a gas space, which enables a pressure-neutral transition of the liquid working medium from the siphon element (14) into the lower area of ​​the return pipe (12). [3] Thermosiphon according to any one of the preceding claims, characterized by , that the spatial separation of the pipe strands (11, 12) and the siphon element (14) eliminates the entrainment limit (countercurrent congestion). [4] Thermosiphon according to any one of the preceding claims, characterized by , that the pipe system is under high vacuum and is filled with an alcohol-based working medium, preferably ethanol (18). [5] Thermosiphon according to any one of the preceding claims, characterized bythat the riser pipe (11) and the return pipe (12) are made of copper pipes, wherein the riser pipe (11) has a larger diameter than the return pipe (12), preferably 54 mm to 42 mm. [6] Thermosiphon according to any one of the preceding claims, characterized by , that the siphon element (14) is dimensioned in such a way that a re-evaporation of the condensate in the return pipe (12) is prevented by the targeted heat extraction at the heat exchanger (15). [7] Thermosiphon according to any one of the preceding claims, characterized by , that the probe foot (13) is designed as a materially bonded U-connection to form a hermetically sealed circuit. [8] Thermosiphon according to any one of the preceding claims, characterized by , that a vacuum connection (16) is arranged between the outlet of the heat exchanger (15) and the siphon element (14) for evacuating and sealing the system. [9] Use of a thermosiphon according to one of claims 1 to 8 as a post-heating stage in the return line of a flat-plate collector or in a parallel cascade circuit of several probes for the monovalent full supply of a heat pump.

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