Heating Installation With Staged Hot-Water Preheating
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Solution Overview
Problem
Existing heating installations inefficiently utilize heat energy, particularly in the final heating steps for tap hot-water, leading to wasted surplus heat and reduced efficiency of heat pumps.
Innovation Solution
A configuration with a first heat pump, a first heat exchanger as a subcooler, a second heat pump, and two series-connected heat exchangers in the second circuit to preheat tap hot-water in successive steps, utilizing both low-grade and high-grade heat energy efficiently, and optionally incorporating an accumulator tank for peak demand management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single heat exchanger is used in the second circuit, then the device complexity is reduced, but the heat energy utilization efficiency deteriorates
Solution Approach 1:
The second circuit is segmented into multiple heat exchangers (first heat exchanger as subcooler, second heat exchanger, and third heat exchanger) arranged in series. Each heat exchanger extracts heat at different temperature levels from the working medium, enabling progressive utilization of heat energy from high-grade to low-grade, thereby resolving the contradiction between energy efficiency and device complexity.
Solution Approach 2:
Different heat exchangers are positioned at different locations in the second circuit to exploit local temperature differences. The first heat exchanger operates where the working medium has high temperature for subcooling, while subsequent heat exchangers operate at progressively lower temperatures for water heating, optimizing heat transfer efficiency at each local position.
2Productivity
If the first heat pump operates at high efficiency, then the heating performance is improved, but the surplus heat waste increases
Solution Approach 1:
The surplus heat from the first heat pump that would normally be wasted is converted into a beneficial resource. The first heat exchanger captures this surplus heat for subcooling the working medium, while subsequent heat exchangers further utilize it for heating water, transforming energy waste into useful heating output and improving overall system efficiency.
Solution Approach 2:
The heat from the first heat pump serves multiple functions: primary heating through the condenser, subcooling through the first heat exchanger, and water heating through the second and third heat exchangers. This multi-functionality allows the system to maximize the utilization of heat energy from a single heat pump source.
3Loss of energy
If two heat exchangers are arranged in series for preheating water, then the heat energy utilization is improved, but the device complexity increases
Solution Approach 1:
The water heating process is segmented into multiple stages using two heat exchangers in series. The second heat exchanger performs initial heating, while the third heat exchanger performs further heating. This segmentation allows progressive extraction of heat energy at different temperature levels, improving overall heat utilization efficiency while distributing the complexity across standardized components.
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 the efficiency of heat energy utilization, allowing for efficient preheating and final heating of tap hot-water, while maintaining efficient cooling and subcooling of the working medium, even when the first heat pump is temporarily out of operation.
Implementation Method 1
a first heat exchanger which is arranged in the second circuit and which is connected between a condenser and an expansion valve of the first heat pump in order to transfer heat from a working medium of the first heat pump to the medium in the second circuit
Implementation Method 2
a second heat pump arranged for heating a medium by absorbing heat energy from the medium in the second circuit
Implementation Method 3
a second heat exchanger which is arranged in the second circuit in order to transfer heat from the medium in the second circuit to water in a water supply line that is intended to be heated in order to provide tap hot-water
Implementation Method 4
a third heat exchanger which is arranged in the second circuit in order to transfer heat from the medium in the second circuit to the water in said water supply line
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A heating installation comprising : - a first circuit (C1); - a second circuit (C2); - a first heat pump (4) for heating the medium in the first circuit; - a first heat exchanger (10) arranged in the second circuit (C2) and connected between a condenser (4b) and an expansion valve (4d) of the first heat pump; - a second heat pump (11) arranged for heating a medium by absorbing heat energy from the medium in the second circuit; and - a second heat exchanger (12) and a third heat exchanger (14) for transferring heat from the medium in the second circuit to water in a water supply line (13). The second heat exchanger (12) is connected to the water supply line upstream of the third heat exchanger (14) in order to allow the second heat exchanger to preheat the tap hot-water in a first step and the third heat exchanger to preheat the tap hot-water in a subsequent second step.