Heat Pump Dryer Startup Heating for Faster Capacity Build-Up
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Solution Overview
Problem
Heat pump dryers experience a significant delay in startup transient due to the inherent inefficiencies in mechanical refrigeration cycles, which affects the drying process and energy consumption.
Innovation Solution
Incorporating an auxiliary heater to provide an artificial load to the evaporator, allowing for accelerated system capacity development by heating the supply air and increasing the evaporator's energy input, thereby reducing the start transient phase and enhancing drying performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If an auxiliary heater is added to accelerate system capacity development, then the startup transient delay is reduced, but the device complexity increases
Solution Approach 1:
The auxiliary heater provides preliminary heating action during the startup transient phase to accelerate system capacity development. By pre-heating the refrigerant and components before the main cooling cycle begins, the system reaches operational capacity faster, reducing the startup delay without requiring complete system redesign
Solution Approach 2:
The system changes operational parameters by introducing controlled heating during startup, which modifies the thermal state of the refrigerant and heat exchangers. This parameter change (from purely cooling to heating-assisted cooling) accelerates the transient response and reduces startup time
2Productivity
If the auxiliary heater is used to heat the evaporator supply, then the system capacity development is accelerated, but the energy consumption increases
Solution Approach 1:
The auxiliary heater operates periodically or intermittently during the startup phase rather than continuously, providing bursts of heating energy when most needed to accelerate capacity development, then shutting off once the system reaches adequate operational temperature, thereby balancing productivity gain with energy consumption
Solution Approach 2:
The auxiliary heater ensures continuous useful action during startup by maintaining heating until the system reaches full capacity, preventing delays and ensuring the cooling cycle begins at optimal conditions, which improves overall system efficiency despite the additional energy input
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 significantly reduces drying time and improves the efficiency of the refrigeration cycle by elevating pressures and temperatures, allowing the system to reach full capacity faster while minimizing energy consumption.
Implementation Method 1
enabling the auxiliary heater to provide an artificial load to an evaporator comprises heating a supply of the evaporator
Implementation Method 2
using the artificial load provided to the evaporator to accelerate system capacity development
Implementation Method 3
a mechanical refrigeration cycle arrangement having a working fluid and an evaporator, a condenser, a compressor
Implementation Method 4
a condenser, a compressor, and an expansion device, cooperatively interconnected and containing the working fluid
Implementation Method 5
a duct and fan arrangement configured to pass air over the condenser
Implementation Method 6
an expansion device, cooperatively interconnected and containing the working fluid
Data Source
AI summary
A method of operating a heat pump clothes dryer operating on a mechanical refrigeration cycle is disclosed. The method includes partitioning all energy available in the heat pump clothes dryer into a first amount of energy and a second amount of energy; using the first amount of energy to attain a standard parameter performance for the heat pump clothes dryer; and using the second amount of energy to accelerate a dry cycle of the heat pump clothes dryer, wherein using the second amount of energy to accelerate a dry cycle of the heat pump clothes dryer comprises using the second amount of energy to energize an auxiliary heater during a start transient phase of the dry cycle to decrease the start transient phase.