Two-Stage Flow-Through Liquid Heater for Low-Power Beverage Machines
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Solution Overview
Problem
Existing liquid heating devices for hot beverage machines face challenges in achieving high flow rates and pressures efficiently while maintaining low power consumption, particularly in producing both regular and espresso coffee, as current boiler and flow-through heating techniques are not suitable for combined machines and are energy-inefficient.
Innovation Solution
A liquid heating device with a two-step heating system using a flow-through heater, a first tank for initial liquid storage, a second tank for pre-heating, and a switching unit to manage between pre-heating and end-heating cycles, pre-heating a portion of the liquid to 35-40°C and then heating it to 90-95°C, reducing overall power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a flow-through heater is used to achieve high flow rates, then the flow rate increases, but the power consumption becomes excessively high (around 2,100 W)
Solution Approach 1:
The heating process is segmented into two distinct stages: a pre-heating stage where liquid is heated to an intermediate temperature (35-40°C) and stored in a second tank, and a final heating stage where the pre-heated liquid is heated to the target temperature (90-95°C). This segmentation allows the flow-through heater to operate at lower power levels during pre-heating while achieving the same overall heating effect, reducing peak power consumption from 2,100 W to acceptable levels for low voltage countries.
Solution Approach 2:
The pre-heating tank performs preliminary heating of the liquid before it reaches the flow-through heater. By pre-heating the liquid to 35-40°C and storing it, the system reduces the temperature differential that the flow-through heater must overcome, thereby reducing the power required during the final heating stage and enabling high flow rates with lower overall power consumption.
2Productivity
If a boiler system is used to achieve high flow rates at low pressures, then the flow rate increases, but the device complexity and manufacturing cost increase significantly
Solution Approach 1:
The system segments the heating function between a simple pre-heating tank and a flow-through heater, avoiding the need for a complex high-pressure boiler system. The pre-heating tank can be a simple insulated container, and the flow-through heater operates at lower pressures, collectively achieving high flow rates without the complexity and safety requirements of high-pressure boiler systems.
Solution Approach 2:
The pre-heating tank acts as an intermediary between the water source and the flow-through heater. It performs the initial heating function that would otherwise require a complex boiler system, allowing the flow-through heater to operate simpler and more efficiently at lower pressures while still achieving the required flow rates.
3Loss of time
If the entire water reservoir is pre-heated to 40°C, then the heating time for coffee production is reduced, but the energy efficiency deteriorates significantly
Solution Approach 1:
The system extracts only the necessary amount of liquid from the main reservoir for pre-heating, rather than heating the entire reservoir. The pre-heating tank has a limited capacity that corresponds to the amount needed for one or a few coffee drinks, so only that specific volume is heated to 40°C. This eliminates the energy waste of heating unused water while still providing the time-saving benefit of having pre-heated water ready.
Solution Approach 2:
The system applies partial pre-heating action by heating only the portion of water that will be immediately used for coffee preparation, rather than heating the entire reservoir. This partial action is sufficient to reduce heating time for the required amount of coffee while avoiding the excessive energy consumption that would result from heating the full reservoir capacity.
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
Enables high flow rates and pressures with lower power usage, suitable for both regular and espresso coffee production, and can be operated in low voltage countries, reducing energy inefficiencies by only heating the amount of liquid needed for the selected beverage.
Implementation Method 1
a flow through heater; a pre-heating cycle, in which liquid flows from the first tank through the flow through heater into the second tank
Data Source
AI summary
The present invention relates to a liquid heating device (10) for a hot beverage machine, comprising: —a flow through heater (18, 18′); —a first tank (12) for receiving liquid (24) to be heated; —a second tank (14) for temporarily storing pre-heated liquid (24′); —a liquid outlet (22) for releasing heated liquid; and —a switching unit (20, 20′, 20″, 20′″) which is configured to switch a liquid-flow cycle of the liquid heating device (10) between a pre-heating cycle, in which liquid (24) flows from the first tank (12) through the flow through heater (18, 18′) and into the second tank (14) in order to temporarily store pre-heated liquid (24′) in the second tank (14), and a end-heating cycle, in which the pre-heated liquid (24′) flows from the second tank (14) through the flow through heater (18, 18′) to the liquid outlet (22).