Hot-water heating system, control device, and control method
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Solution Overview
Problem
Existing hot water heating systems face issues with energy conservation and comfort due to repeated start-stop cycles of the heat source unit, which can reduce durability and increase time to stabilize room temperature, especially in well-insulated buildings, as they do not consider the thermal properties of the building in heat supply commands.
Innovation Solution
A hot water heating system with a controller that calculates and updates heat supply commands based on thermal properties of the building, using a compressor ON gain and OFF gain to maintain continuous temperature control from heating off to on states, ensuring energy conservation without compromising comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a preset heat supply command is used without considering thermal properties of the building, then the control system is simple, but the hot-water discharge temperature may exceed upper limit or not rise sufficiently, causing repeated start-stop cycles or insufficient heating
Solution Approach 1:
The patent applies parameter changes by calculating building-specific thermal parameters (thermal mass, heat loss coefficient, time constant) and using these parameters to dynamically adjust the heat supply command. The controller changes control parameters based on building characteristics rather than using fixed preset values, resolving the contradiction between simple control and reliable heating.
2Loss of energy
If the heat source unit is stopped for energy conservation when room temperature is sufficient, then energy consumption is reduced, but the durability of the actuator decreases due to repeated start-stop cycles
Solution Approach 1:
The patent applies preliminary action by using the calculated time constant to predict when the room temperature will fall below the set point and proactively restarting the heat source unit before the temperature drops. This prevents the temperature from falling and avoiding the need for frequent start-stop cycles, thus protecting the actuator while maintaining energy efficiency.
Solution Approach 2:
The system applies beforehand cushioning by incorporating the building's thermal mass and time constant into the control algorithm, which cushions against temperature fluctuations. The controller uses this thermal inertia information to maintain more stable operation patterns, reducing mechanical stress on actuators from repeated cycling.
3Device complexity
If feedback control starts from the beginning when the heat source unit resumes operation, then the control is simple, but the time taken to stabilize the room temperature increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating the building's thermal characteristics during initial system operation and storing these parameters for future use. When the heat source unit resumes operation, the controller uses these pre-calculated parameters to immediately optimize the heat supply command, avoiding the need to restart the feedback control learning process and thus reducing temperature stabilization time.
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
The system achieves energy conservation while maintaining room temperature comfort by using gain-based control to optimize heat supply, reducing the need for frequent start-stop cycles and improving heating control accuracy.
Implementation Method 1
a refrigerant-water heat exchanger configured to exchange heat between the refrigerant and water
Implementation Method 2
a compressor configured to compress refrigerant
Implementation Method 3
a circulation pump configured to circulate the hot water between the refrigerant-water heat exchanger and the indoor unit
Implementation Method 4
an indoor unit configured to reject heat of hot water generated by the heat source unit and heat the building
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A hot water heating system includes a room temperature sensor that detects room temperature information of a building; a heat source unit that generates hot water; an indoor unit that rejects heat of hot water generated by the heat source unit and heats the building; and a controller that controls the heat source unit. The controller includes a control gain determination unit that calculates a first gain and a second gain based on thermal properties of the building, a heating control unit that updates a hot-water discharge temperature command corresponding to a target value of a temperature of water at an outlet of a refrigerant-water heat exchanger by using the first gain and the second gain, and a hot-water discharge temperature control unit that, in a case of air-conditioning ON in which the indoor unit supplies heat to the building, outputs a heat supply command to the heat source unit based on the hot-water discharge temperature command updated by the heating control unit. The first gain is designed so that the hot-water discharge temperature command that results in intended room temperature response in the case of air-conditioning ON is obtained, and the second gain is designed so that the hot-water discharge temperature command reflecting a change in room temperature in a case of air-conditioning OFF in which the indoor unit does not supply heat to the building is obtained. The heating control unit updates, in the case of air-conditioning ON, the hot-water discharge temperature command by using a setting temperature for room temperature, the room temperature information, and the first gain, and updates, in the case of air-conditioning OFF, the hot-water discharge temperature command by using the setting temperature, the room temperature information, and the second gain.