Heat Exchanger with Upper-Part Manifolds for PCM Storage
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Solution Overview
Problem
Conventional thermal energy storage systems using Phase Change Materials (PCMs) face challenges in heat transfer efficiency due to low thermal conductivity and complex, costly assembly processes, particularly in heat exchangers with bulky connections and dead volumes.
Innovation Solution
A thermal energy storage device utilizing a two-phase liquid-gas heat transfer fluid that circulates through the exchanger, with connections and evacuations managed from the upper part, reducing dead volumes and facilitating easier assembly, and incorporating expansion compensators for sealing and expansion compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heat exchangers with tubes and bulky connections are used, then heat transfer surface area is increased, but device complexity and manufacturing cost increase
Solution Approach 1:
The heat exchanger is divided into multiple independent modules, each containing a subset of tubes connected to common distribution and collection manifolds. This modular segmentation simplifies assembly by allowing individual modules to be manufactured and installed separately, reducing overall device complexity while maintaining adequate heat transfer surface area through the distributed tube arrangement.
Solution Approach 2:
The distribution and collection manifolds serve multiple functions simultaneously: they distribute heat transfer fluid to multiple tubes, collect fluid from tubes, provide structural support for tube attachment, and enable modular assembly configurations. This multi-functionality reduces the need for separate components, simplifying the overall device structure.
2Ease of operation
If tube connections are made at both ends with hydraulic octopus, then heat transfer fluid circulation is enabled, but dead volume increases and assembly becomes more difficult
Solution Approach 1:
The complex hydraulic octopus connection system is replaced by extracting the essential function of fluid distribution and collection into simple manifold structures. The manifolds provide direct, compact connections to tube ends without the bulky multi-branch hydraulic octopus configuration, eliminating dead volume while maintaining fluid circulation capability through the heat exchanger.
Solution Approach 2:
Instead of connecting tubes to a central hydraulic octopus at both ends, the invention inverts the approach by using linear distribution and collection manifolds that run along the tube array. Fluid enters through inlet manifolds, distributes to tubes along their length, collects through outlet manifolds, and exits, eliminating the need for end-to-end hydraulic octopus connections and reducing dead volume.
3Quantity of substance
If PCMs are used for latent heat storage, then energy density is doubled, but thermal conductivity remains low limiting heat transfer
Solution Approach 1:
Metallic tubes filled with high thermal conductivity heat transfer fluid serve as intermediary heat transfer pathways through the PCM. These tubes act as thermal conduits that bypass the low conductivity of the PCM material, efficiently conducting heat from the heat transfer fluid to the surrounding PCM and enabling effective latent heat storage despite the PCM's inherent low thermal conductivity.
Solution Approach 2:
The heat exchanger employs composite construction with metallic tube materials providing high thermal conductivity pathways embedded within the PCM medium. This composite arrangement combines the high conductivity of metals with the high energy density of latent heat storage materials, creating a hybrid system that overcomes the thermal conductivity limitation of pure PCM while maintaining its energy density advantage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances heat transfer efficiency, reduces manufacturing costs, and allows for more efficient storage and retrieval of latent thermal energy, maintaining constant temperature during discharge and minimizing thermal losses.
Implementation Method 1
The heat transfer fluid is a two-phase fluid in a liquid state and a gaseous state intended to circulate in the exchanger
Implementation Method 2
The heat exchanged is called enthalpy of phase change or latent heat and the quantity of energy is of the order of 200 J/g
Implementation Method 3
The two fluids exchange energy by conduction through the thickness of the tubes
Implementation Method 4
Latent storage uses Phase Change Materials (PCM) to store heat. Thermal storage is carried out by storage by enthalpy of change of state
Implementation Method 5
It is the enthalpy of phase change, most often during the solid/liquid state change, which is stored
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
The invention relates to a heat exchanger (1) comprising a heat transfer fluid, which can at least partially extend down into a tank (14) containing a phase change material (PCM) (13), said heat exchanger comprising: a plurality of tubes (2), each tube (2) having a first end (3) that can be arranged in the upper part of the exchanger (1) and a second end (4) that can be arranged in the lower part of the exchanger (1); a distributor (5) establishing a fluid communication between the first ends (3); a manifold (6) establishing a fluid communication between the second ends (4), said distributor (5) comprising an open pipe (7) for supplying or discharging the heat transfer fluid to/from the exchanger (1), said manifold (6) comprising an open pipe (8) for supplying or discharging the heat transfer fluid to/from the exchanger (1). The heat exchanger is characterised in that the heat transfer fluid is a two-phase fluid with a liquid state and a gaseous state that can flow through the exchanger (1), and in that the pipe (8) of the manifold (6) and the pipe (7) of the distributor (5) are configured to open at the upper part of the exchanger (1). The invention is suitable for use in thermal storage systems (TSS) using phase change materials (PCM). More specifically, the invention relates to the integration of a thermal storage system into concentrating solar power systems, for example for direct steam generation power plants, or the recovery of fatal heat from industry.