Vertical Coffee Boiler with Indirect Heating Against Lime Scale
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Solution Overview
Problem
Boilers for coffee vending machines face issues such as lime precipitation, difficulty in cleaning, blockage of hot water outlet pipes, and resistance rupture due to chlorine, primarily because the resistance is in direct contact with water, leading to calcareous scale deposition and inaccurate temperature measurements.
Innovation Solution
A vertically placed boiler design with an integrated resistance and a metal plate for heat transfer, where the resistance is not in direct contact with water, featuring a tubular element to slow water flow and prevent direct cold water entry to the outlet, and a temperature probe positioned externally to avoid lime deposition, using stainless steel and aluminium for durability and ease of cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the resistance is in direct contact with water to heat it, then heating efficiency is improved, but lime deposition and resistance rupture occur
Solution Approach 1:
A metal plate is introduced as an intermediary between the resistance and water. The resistance heats the metal plate, which in turn heats the water through thermal conduction. This mediator prevents direct contact between the resistance and water, eliminating lime deposition on the resistance while maintaining efficient heat transfer to the water.
2Productivity
If the resistance is in direct contact with water, then rapid heat transfer is achieved, but cleaning difficulty and maintenance problems increase
Solution Approach 1:
The metal plate serves as a removable intermediary component that can be easily detached and cleaned. It concentrates lime deposits on its surface rather than on the resistance, making maintenance simpler. The plate can be removed and cleaned separately without disassembling the entire heating system.
3Use of energy by moving object
If narrow tubes are used for water circulation to increase heat exchange, then heating efficiency is improved, but blockage risk increases
Solution Approach 1:
The metal plate acts as a heat exchange intermediary with larger surface area, eliminating the need for narrow tubes. Water flows over or against the plate surface, providing sufficient heat exchange area without constriction, thus preventing blockages while maintaining efficient heating.
4Measurement precision
If temperature sensors are placed in direct contact with water for accurate measurement, then measurement accuracy is improved, but sensor deterioration from lime deposition occurs
Solution Approach 1:
The metal plate serves as both a heat transfer mediator and a protective barrier for temperature sensors. Sensors can be positioned to measure water temperature through or near the plate without direct exposure to water, preventing lime deposition on the sensors while maintaining measurement accuracy.
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 design prevents lime deposition, facilitates easy cleaning, maintains accurate temperature measurements, and ensures efficient heat transfer while being resistant to corrosion and fatigue, improving energy efficiency and safety.
Implementation Method 1
a first body (1) provided with an electrical resistance (2) integrated therein
Implementation Method 2
a metal plate (4) linked to the outer face (3) of the first body (1) receiving heat from same
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a boiler for coffee vending machines, intended for being placed vertically inside a coffee machine and for heating water to prepare coffee, wherein the resistance is not in direct contact with water and it is ensured that water which is evacuated from the boiler is at the suitable temperature, wherein the boiler comprises a first metal body (1) provided with an electrical resistance (2) integrated therein, a metal plate (4) linked to the first body (1) receiving heat from same, and a second partially convex body (5) linked on the perimeter to the outer face (3) of the first body (1) and defining with the plate (4) a water tank (6) which is provided with a through inlet cavity (8) arranged facing the plate (4) and an outlet cavity (10).