Heat Pump Dryer Circuit Heating for Compressor Liquid Protection
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Solution Overview
Problem
Tumble dryers with heat pump circuits face issues of liquid medium being sucked into the compressor, leading to potential damage and inefficiencies due to additional heaters causing flow resistance and fluff ignition risks.
Innovation Solution
Incorporating a heater within the heat pump circuit, controlled by a temperature difference-based system to prevent liquid medium suction and optimize heating, allowing for efficient energy supply without additional heating in the process circuit, and featuring a compact and cost-effective design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an additional heater is installed in the process circuit to rapidly raise temperature, then the heating efficiency is improved, but the device complexity increases and fluff ignition risk arises
Solution Approach 1:
The heater is extracted from the process circuit and relocated to the heat pump circuit. This removes the source of fluff ignition risk and flow resistance problems while maintaining the temperature control function. The heater now operates on the refrigerant side where it cannot contact laundry fluff and creates minimal flow resistance.
Solution Approach 2:
The heat pump circuit acts as an intermediary between the heater and the process circuit. The heater heats the refrigerant in the heat pump circuit, and this thermal energy is then transferred to the process air through the condenser and evaporator, providing indirect heating that avoids direct contact between the heater and process air contaminants.
2Reliability
If a heater is installed in the process circuit to prevent liquid medium suction, then the compressor protection is improved, but the flow resistance increases and system reliability deteriorates
Solution Approach 1:
The heater is extracted from the process circuit and placed in the heat pump circuit between the evaporator and compressor. This location provides direct protection against liquid medium suction while avoiding the introduction of flow resistance into the process air path, as the heater now only affects the refrigerant flow.
Solution Approach 2:
The heating function is localized to the specific section of the heat pump circuit where liquid medium suction risk exists (between evaporator and compressor). This targeted approach provides compressor protection without unnecessarily heating other parts of the system or introducing flow resistance into the process circuit.
3Temperature
If a heater is installed in the process circuit to provide additional heating, then the temperature control is improved, but the system becomes susceptible to dirt and fluff accumulation
Solution Approach 1:
The heater is extracted from the process circuit environment where it would be exposed to dirt and fluff, and relocated to the sealed heat pump circuit. This protects the heater from contamination while maintaining its temperature control function through refrigerant heating.
Solution Approach 2:
The refrigerant serves as an intermediary medium that transfers thermal energy from the heater to the process air without direct contact. This indirect heating mechanism maintains temperature control capability while preventing the heater from being contaminated by process air particles.
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
Prevents liquid medium suction, reduces the risk of compressor damage, enhances drying efficiency by quickly reaching optimal temperatures, and maintains system cleanliness by avoiding fluff accumulation and clogging.
Implementation Method 1
a heater (9) is provided in the heat pump circuit... Energy can thus be supplied to the system via the heat pump circuit
Implementation Method 2
The evaporator (6) is used to cool the process air and in this way remove water from it, while the condenser (3) is used to reheat the process air
Implementation Method 3
an additional heat exchanger (4) is advantageously arranged, with which heat can be extracted from the heat pump circuit... a fan (7) is provided, with which ambient air is guided over the additional heat exchanger (4) in order to cool it
Data Source
Figure 1
AI summary
The dryer has a controller (8), and a drum (1) for accommodating clothes to be dried. A process circuit conducts heated process air through the drum for cooling the process air for dewatering and for reheating the process air. A heat pump circuit conducts a medium e.g. liquid medium, through a condenser (3), a throttle (5), an evaporator (6) and a compressor (2). The process air is heatable by the condenser and coolable by the evaporator. A heater (9) is arranged in the heat pump circuit between the evaporator and the compressor .