Method for operating a heat pump unit and heat pump unit
Solution Overview
Problem
Existing heat pump systems lack an efficient method to adjust heat output in response to varying outside temperatures, leading to increased heat output with higher temperatures, which results in a decrease in the maximum water temperature that can be reached in hot water tanks.
Innovation Solution
A method and heat pump unit that determines outside temperature and switches between operating modes, reducing the speed of the evaporator fan or compressor and controlling the electronic expansion valve to decrease the mass flow in the refrigerant circuit when temperatures rise above a certain limit, thereby adjusting the heat output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the heat pump operates at full output when outside temperature increases, then the heating capacity is maximized, but the maximum water temperature in hot water tanks decreases
Solution Approach 1:
The patent applies dynamics by making the heat pump output adjustable rather than fixed. The control device dynamically adjusts the mass flow of refrigerant and the operation of the compressor and expansion valve based on outside temperature conditions, allowing the system to transition between different operating states (first and second operating modes) to maintain optimal water temperature while adapting to environmental changes
Solution Approach 2:
The patent changes key operating parameters including refrigerant mass flow rate, compressor speed, and expansion valve opening based on outside temperature. By adjusting these parameters, the system reduces refrigerant circulation and compressor workload when outside temperature is high, thereby controlling the heating output to prevent excessive heat that would lower the maximum achievable water temperature
2Power
If the refrigerant mass flow is increased to provide more heating, then the heat output increases, but the energy efficiency decreases
Solution Approach 1:
The patent implements feedback control where the control device continuously monitors outside temperature and adjusts the refrigerant mass flow and compressor operation accordingly. This closed-loop control ensures the heat pump operates at optimal efficiency by matching output to actual heating needs based on environmental conditions, avoiding energy waste from excessive refrigerant circulation
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 approach allows for improved adjustment of heat output, preventing a decrease in the maximum water temperature in hot water tanks by reducing heating output when outside temperatures increase, maintaining efficient operation.
Implementation Method 1
an evaporator (40) through which a refrigerant flows
Implementation Method 2
a compressor (20) for compressing the refrigerant
Implementation Method 3
a hot water tank (not visible in diagram) into which hot water can be fed
Implementation Method 4
an electronic expansion valve (60, 100) for controlling the mass flow rate of the refrigerant
Data Source
Figure 1
AI summary
A method for controlling a heat pump unit is provided. The heat pump unit comprises a condenser (10), a compressor (20), an evaporator (40), and an electronic expansion valve (60). The outside temperature is determined, and the heat pump unit operates in a first operating mode when the outside temperature is below a first limit value. The heat pump unit operates in a second operating mode when the outside temperature is above the first limit value. In the second operating mode, the speed of the evaporator fan (40) or the speed of the compressor (20) is reduced, and/or the electronic expansion valve (60) is controlled such that a lower mass flow rate is present in the refrigerant circuit.