Hot Gas Evaporator Defrosting for Frost-Resistant Absorption Heat Pumps
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Solution Overview
Problem
Absorption heat pumps experience reduced efficiency and heat supply when ambient air temperature drops below 0°C due to frost or ice forming on the outside air heat exchanger, which acts as a heat insulator, hindering heat absorption.
Innovation Solution
A hot gas line branches off from the condenser to bypass the condenser and expansion valve, allowing hot coolant vapor to directly heat the evaporator, initiating a defrosting operation by heating the evaporator and outside air heat exchanger above normal operating temperatures, thereby thawing the insulating ice layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the absorption heat pump operates in cold ambient conditions, then heat supply to consumer is maintained, but frost or ice forms on the outside air heat exchanger reducing heat absorption efficiency
Solution Approach 1:
The patent converts the harmful cold ambient condition that causes icing into a beneficial defrosting mechanism by using the hot coolant vapor from the generator to heat the evaporator and melt the ice layer on the outside air heat exchanger, thus turning the problematic cold environment into part of the solution
2Object-affected harmful factors
If hot coolant vapor is supplied to the evaporator for defrosting, then the ice layer on the outside air heat exchanger is thawed, but the condenser cooling function is bypassed
Solution Approach 1:
The patent implements a dynamic flow path configuration where the coolant vapor can be directed either through the condenser during normal operation or directly to the evaporator during defrosting mode, allowing the system to adapt its structure to different operational requirements
3Productivity
If the evaporator is heated above normal operating temperature for defrosting, then heat absorption efficiency is restored, but energy consumption increases
Solution Approach 1:
The system uses its own hot coolant vapor from the generator to defrost the evaporator, rather than requiring an external energy source, thus the defrosting process is self-servicing and does not significantly increase overall energy consumption
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 solution effectively defrosts the outside air heat exchanger, restoring efficient heat absorption and supply by ensuring the evaporator operates above its normal temperature, thus maintaining the absorption heat pump's efficiency even in cold conditions.
Implementation Method 1
a heat source (10) to heat the generator (20) in order to drive a coolant vapor out of a solution which is contained in the generator (20)
Implementation Method 2
the removed coolant vapor is supplied to a condenser (30) which cools the coolant vapor as heat is released to a consumer and in doing so condenses the coolant vapor
Implementation Method 3
the coolant fluid is supplied to an expansion valve (40) which expands the coolant fluid
Implementation Method 4
the expanded coolant fluid is supplied to an evaporator (50) for at least partial evaporation of the expanded coolant fluid against a medium
Implementation Method 5
the coolant fluid is supplied to an absorber (60) where it is absorbed from the coolant-poor solution
Implementation Method 6
a hot gas line which branches off the line for coolant vapor from the condenser and is fluid-connected to the evaporator such that it bypasses the condenser and the expansion valve
Data Source
AI summary
An absorption heat pump having a generator, a heat source to heat the generator to drive coolant vapor out of solution, a condenser for cooling the coolant vapor and an expansion valve that expand the coolant fluid as well as an evaporator for at least partial evaporation of the expanded coolant fluid against a medium which is connected to at least one absorber which absorbs the expanded coolant fluid. A hot gas line which branches off from a line for coolant vapor upstream of the condenser and is fluid-connected to the evaporator such that it bypasses the condenser and the expansion valve, a defrosting valve being provided in the hot gas line, by means of which the flow of coolant vapor through the hot gas line can be controlled. The absorption heat pump is operated in a cyclic circulation process.