EP0893663A1 - A method of controlling the defrosting cycles in a heat heat-pump system - Google Patents
A method of controlling the defrosting cycles in a heat heat-pump system Download PDFInfo
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- EP0893663A1 EP0893663A1 EP97830379A EP97830379A EP0893663A1 EP 0893663 A1 EP0893663 A1 EP 0893663A1 EP 97830379 A EP97830379 A EP 97830379A EP 97830379 A EP97830379 A EP 97830379A EP 0893663 A1 EP0893663 A1 EP 0893663A1
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- Prior art keywords
- value
- heat
- threshold value
- predetermined
- defrosting cycle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
- F25D21/002—Defroster control
- F25D21/006—Defroster control with electronic control circuits
Definitions
- the present invention relates to a method of controlling the defrosting cycles in a heat-pump system and, in particular, to a method according to the preamble of the first claim.
- a heat pump is a thermal machine which, with an expenditure of mechanical work, draws a quantity of heat from an outside environment (a source) and sends all of the thermal energy into an inside environment (a recipient) so as to heat it.
- the heat pump can also operate in reverse as a cooler, taking thermal energy from the inside environment (source) so as to cool it.
- a problem with heat-pump systems in which an air heat-exchanger (a battery) is used in the outside environment is that, when the temperature of a surface of the battery which is contact with the outside environment falls below 0°C, a layer of frost forms on the battery owing to atmospheric water vapour. This layer of frost obstructs the flow of air through the battery, compromising the exchange of heat.
- Known heat-pump systems have a transducer which periodically measures the value of a state parameter (pressure or temperature) of a refrigerant fluid passing through the outside battery, or the temperature of the surface of the battery which is in contact with the outside environment. When this measurement falls below a predetermined threshold value, the heat-pump system performs a defrosting cycle, for example, by reversing the operation of the system. The outside battery is thus heated (taking heat from the inside environment) and melts the frost formed thereon.
- a state parameter pressure or temperature
- a disadvantage of known heat-pump systems is that, particularly when the outside temperature and the relative humidity value are low, the defrosting cycle is triggered even when the outside battery is not frosty; unnecessary defrosting cycles are therefore performed, consequently reducing the output of the system as a whole.
- the object of the present invention is to prevent the aforementioned drawbacks. To achieve this object, a method as described in the first claim is proposed.
- the method of the present invention triggers the defrosting cycle in dependence on the actual conditions of the outside battery.
- the frequency of the defrosting cycles can thus be reduced considerably. This achieves a greater output and improved performance of the heat-pump system with a consequent considerable energy saving.
- a heat-pump system is constituted, in particular, by an air-conditioner for winter heating and for summer cooling; the method of the present invention may, however, also be used in different applications, for example, in a central heating plant, in a distillation device, etc.
- the heat-pump system 100 uses a refrigerant fluid (for example, Freon) which is subjected to a thermodynamic cycle (as described in detail below) and which flows through a circuit 103 formed by suitable pipes.
- the heat-pump system 100 includes a heat exchanger 130 which is in contact with an outside environment and which operates as a heat source or as a heat recipient during winter and summer, respectively.
- the exchange of heat takes place in air; in particular, the heat exchanger 130 (the battery) is constituted by pipes, generally having fins, the refrigerant fluid flowing through the pipes and the air passing over them externally.
- the air circulation is forced by means of a fan 135 or takes place by natural convection.
- a similar battery 140 in contact with an inside environment operates as a heat recipient or a heat source in winter and in summer, respectively; a fan 145 forces, for example, the air circulation in the inside environment from an intake duct 150 to an outlet duct 153.
- the present invention may, however, also be used with internal heat exchangers of different types, for example, with an exchange of heat in water, in the floor, etc.
- the heat-pump system 100 is constituted by a single body; alternatively, two separate units are provided in the outside environment and in the inside environment, respectively.
- a compressor unit 150 connected by means of a three-way valve (not shown in the drawing) for the winter-summer reversal of the circuit 103, and two expansion valves 155, 156 (or, alternatively, small calibrated holes or sections of capillary tube) for the winter and summer refrigerant-fluid circuits, respectively.
- a transducer 160 periodically measures a state parameter relating to the refrigerant fluid and supplies a value S indicative of this measurement to an electronic microprocessor board 165 (or other equivalent logic means).
- a temperature transducer with a defrosting probe disposed inside the battery 130 is used; alternatively, the temperature transducer is disposed in the inside battery 140, or a pressure transducer is used.
- the microprocessor 165 is connected to the compressor 150 in order to control the operation of the heat-pump system 100 by means of suitable control signals and to perform a cycle for defrosting the outside battery 130.
- the refrigerant fluid in the vapour state at the output of the outside battery 130 is compressed in the unit 150.
- the battery 140 operates as a condenser in which the refrigerant fluid cools until it condenses to the liquid state, supplying heat to the inside environment 120.
- the refrigerant fluid then expands with partial vaporization in the valve 155 so as to regulate the flow-rate of the refrigerant fluid so that it is completely vaporized in the battery 130 (which acts as an evaporator) owing to the heat taken from the outside environment.
- the present invention may also be used in a water-vapour, air, or absorption system etc.
- a defrosting cycle is performed periodically (as described in detail below) in order to melt a layer of frost deposited on an outside surface of the battery 130.
- the operation of the system 100 is reversed, so that the outside battery 130 (acting as a condenser) is heated, melting the frost.
- the operation of the heat-pump system 100 is interrupted and the frost is melted by electrical heating, by a flow of air or of water at a suitable temperature, or by the injection of hot gas coming from inside the outside battery.
- a method 200 of controlling the defrosting cycles in the heat-pump system described above starts in box 203, in which the system is activated, for example, when it is switched on, when it leaves a stand-by state, or when it starts up again after a thermostatic intervention to regulate the temperature of the inside environment.
- a parameter S Th which represents a threshold temperature for the implementation of the defrosting cycle is set at a predetermined initial (default) value, for example, equal to a few degrees centigrade below zero, such as -2°C.
- a parameter T Wait which represents a minimum waiting time between two consecutive defrosting cycles or between the activation of the system and a first defrosting cycle (used for limiting the repetition of the defrosting cycles with regard to time) is preferably set at a further predetermined initial value, for example, of a few minutes, such as 15 minutes. It should be noted that, in general, the time is measured in relation to the operation of the heat-pump system, for example, as the period of operation of the compressor.
- the method checks whether a first defrosting cycle has been carried out since the heat-pump system was activated; this preferably enables the parameters (S Th and T Wait ) of the system to be modified only after this first defrosting cycle. If the answer is negative, the method goes on to box 212 (described below). If the answer is affirmative, the method checks, in box 215, whether the operating time T D which has elapsed since the last defrosting cycle exceeds a predetermined minimum value, for example, of a few minutes, such as 10 minutes; the system parameters are preferably modified only after this operating period, so as to allow the system to reach a steady state.
- the method goes directly to box 212. If the operating time T D since the last defrosting cycle is greater than 10 minutes, the method according to the present invention calculates a value correlated with a maximum value of the measured temperature S. In a preferred embodiment, an average value of the measured temperatures S is calculated periodically for this purpose. For example, in the box 221, an average value S Ave of the temperatures S measured since a last modification cycle is updated. The method then goes on to box 223 in which it is checked whether a predetermined period of time, for example of 1 minute, has elapsed since a last modification cycle. If the answer is negative, the method goes directly to box 212.
- a predetermined period of time for example of 1 minute
- the method then goes on to box 224 in which it is checked whether the average value S Ave is greater than a maximum temperature value S Max (set initially at an invalid value). If the answer is affirmative, in box 227 the value S Max is set at the average value S Ave and the method then goes on to box 230. If the average value S Ave is not greater than the maximum value S Max , the method goes directly to box 230.
- the method according to the present invention modifies the parameter S Th which is representative of the threshold temperature for performing the defrosting cycle in dependence on the maximum value S Max ;
- the parameter S Th is preferably set at the maximum value S Max minus a predetermined value, for example, of a few degrees centigrade, such as 3°C.
- the parameter T Wait which is representative of the minimum waiting time between two consecutive defrosting cycles is advantageously modified in dependence on the value of the parameter S Th .
- the method checks whether the parameter S Th is below a predetermined minimum value, for example, of a few degrees centigrade below zero, such as -4°C. If the answer is negative, the method goes directly to box 212. If the parameter S Th is below the minimum value, the parameter T Wait is set at a higher predetermined value, for example, 45 minutes, in box 236. The method then goes on to box 212.
- the method checks whether a defrosting cycle is in operation. If not, the method goes to box 239 in which it is checked whether the measured temperature S is below the parameter S Th and whether the time T D since the last defrosting cycle (or since the activation of the system) is greater than the parameter T Wait . If at least one of these conditions is not satisfied, the method goes to box 242 (described below).
- the method goes to box 245 in which a defrosting cycle is started, for example, by the reversal of the operation of the heat-pump system; if this is the first defrosting cycle, the parameter T Wait is also modified, preferably to a predetermined value, for example, of 30 minutes, between the initial value (15 minutes) and the value set in box 236 (45 minutes). The method then goes to box 242.
- a defrosting cycle is started, for example, by the reversal of the operation of the heat-pump system; if this is the first defrosting cycle, the parameter T Wait is also modified, preferably to a predetermined value, for example, of 30 minutes, between the initial value (15 minutes) and the value set in box 236 (45 minutes).
- the method preferably controls the duration of this operation. For example, in box 248 it is checked whether a predetermined minimum time T Min , for example, of 2.5 minutes, has elapsed since the start of the defrosting cycle. In general, it is in fact preferable for the defrosting cycle to have a minimum duration since excessively frequent reversals of the operation of the heat-pump system may cause excessive leakage of oil in the compressor with consequent damage to the system. If the minimum defrosting time T Min has not elapsed, the method goes directly to box 242.
- T Min for example, of 2.5 minutes
- the method goes to box 251 in which it is checked whether the measured temperature S is greater than a predetermined maximum end of defrosting temperature S End , for example, of a few tens of degrees centigrade, such as 20°C, or whether a predetermined maximum time T Max , for example, of 6 minutes, has elapsed since the start of the defrosting cycle. If at least one of these conditions is satisfied, the defrosting cycle is terminated in box 253 and the method then goes to box 242. If neither of the conditions is satisfied, however, the method goes directly to box 242.
- the method preferably checks whether the time T D which has elapsed since the last defrosting cycle is greater than a predetermined maximum value, for example of a few tens of minutes, such as 90 minutes. If not, the method returns to box 207 in order to repeat the steps described above. If a longer time has elapsed, however, the method goes back to box 206 so as to reset the initial values of the parameters of the system.
- a predetermined maximum value for example of a few tens of minutes, such as 90 minutes.
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- Combustion & Propulsion (AREA)
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Abstract
A method (200) of controlling the defrosting
cycles of a battery in a heat-pump system,
comprising the steps of detecting (207) a first
value indicative of a state parameter relating to a
refrigerant fluid used in the system, comparing
(239) the first value with a threshold value, and
performing (245) a defrosting cycle in dependence on
a result of the comparison, includes the steps of
determining (221-227) a second value correlated with
a maximum value of the first value and modifying
(230) the threshold value in dependence on the
second value.
Description
The present invention relates to a method of
controlling the defrosting cycles in a heat-pump
system and, in particular, to a method according to
the preamble of the first claim.
A heat pump is a thermal machine which, with an
expenditure of mechanical work, draws a quantity of
heat from an outside environment (a source) and
sends all of the thermal energy into an inside
environment (a recipient) so as to heat it.
Typically, the heat pump can also operate in reverse
as a cooler, taking thermal energy from the inside
environment (source) so as to cool it.
A problem with heat-pump systems in which an
air heat-exchanger (a battery) is used in the
outside environment is that, when the temperature of
a surface of the battery which is contact with the
outside environment falls below 0°C, a layer of frost
forms on the battery owing to atmospheric water
vapour. This layer of frost obstructs the flow of
air through the battery, compromising the exchange
of heat.
Known heat-pump systems have a transducer which
periodically measures the value of a state parameter
(pressure or temperature) of a refrigerant fluid
passing through the outside battery, or the
temperature of the surface of the battery which is
in contact with the outside environment. When this
measurement falls below a predetermined threshold
value, the heat-pump system performs a defrosting
cycle, for example, by reversing the operation of
the system. The outside battery is thus heated
(taking heat from the inside environment) and melts
the frost formed thereon.
A disadvantage of known heat-pump systems is
that, particularly when the outside temperature and
the relative humidity value are low, the defrosting
cycle is triggered even when the outside battery is
not frosty; unnecessary defrosting cycles are
therefore performed, consequently reducing the
output of the system as a whole.
The object of the present invention is to
prevent the aforementioned drawbacks. To achieve
this object, a method as described in the first
claim is proposed.
The method of the present invention triggers
the defrosting cycle in dependence on the actual
conditions of the outside battery. The frequency of
the defrosting cycles can thus be reduced
considerably. This achieves a greater output and
improved performance of the heat-pump system with a
consequent considerable energy saving.
Further characteristics and advantages of the
method according to the present invention will
become clear from the following description of a
preferred embodiment thereof, given by way of non-limiting
example, with reference to the appended
drawings, in which:
With reference, in particular, to Figure 1, a
heat-pump system, indicated 100, is constituted, in
particular, by an air-conditioner for winter heating
and for summer cooling; the method of the present
invention may, however, also be used in different
applications, for example, in a central heating
plant, in a distillation device, etc. The heat-pump
system 100 uses a refrigerant fluid (for example,
Freon) which is subjected to a thermodynamic cycle
(as described in detail below) and which flows
through a circuit 103 formed by suitable pipes.
The heat-pump system 100 includes a heat
exchanger 130 which is in contact with an outside
environment and which operates as a heat source or
as a heat recipient during winter and summer,
respectively. The exchange of heat takes place in
air; in particular, the heat exchanger 130 (the
battery) is constituted by pipes, generally having
fins, the refrigerant fluid flowing through the
pipes and the air passing over them externally.
Typically, the air circulation is forced by means of
a fan 135 or takes place by natural convection.
A similar battery 140 in contact with an inside
environment operates as a heat recipient or a heat
source in winter and in summer, respectively; a fan
145 forces, for example, the air circulation in the
inside environment from an intake duct 150 to an
outlet duct 153. The present invention may,
however, also be used with internal heat exchangers
of different types, for example, with an exchange of
heat in water, in the floor, etc.
In the embodiment in question, the heat-pump
system 100 is constituted by a single body;
alternatively, two separate units are provided in
the outside environment and in the inside
environment, respectively.
Between the outside battery 130 and the inside
battery 140 there is a compressor unit 150 connected
by means of a three-way valve (not shown in the
drawing) for the winter-summer reversal of the
circuit 103, and two expansion valves 155, 156 (or,
alternatively, small calibrated holes or sections of
capillary tube) for the winter and summer
refrigerant-fluid circuits, respectively.
A transducer 160 periodically measures a state
parameter relating to the refrigerant fluid and
supplies a value S indicative of this measurement to
an electronic microprocessor board 165 (or other
equivalent logic means). In a particularly
inexpensive embodiment, a temperature transducer
with a defrosting probe disposed inside the battery
130 is used; alternatively, the temperature
transducer is disposed in the inside battery 140, or
a pressure transducer is used. The microprocessor
165 is connected to the compressor 150 in order to
control the operation of the heat-pump system 100 by
means of suitable control signals and to perform a
cycle for defrosting the outside battery 130.
In winter when the system 100 is operating as
a heat pump, the refrigerant fluid in the vapour
state at the output of the outside battery 130 is
compressed in the unit 150. In this condition, the
battery 140 operates as a condenser in which the
refrigerant fluid cools until it condenses to the
liquid state, supplying heat to the inside
environment 120. The refrigerant fluid then expands
with partial vaporization in the valve 155 so as to
regulate the flow-rate of the refrigerant fluid so
that it is completely vaporized in the battery 130
(which acts as an evaporator) owing to the heat
taken from the outside environment. In summer, on
the other hand, when it is operating as a cooler,
the outside battery 130 acts as a condenser; the
refrigerant fluid expands partially in the valve 156
and the inside battery 140 acts as an evaporator so
as to take heat from the inside environment. As an
alternative to the above-described vapour
compression system, however, the present invention
may also be used in a water-vapour, air, or
absorption system etc.
In winter, when the system 100 is operating as
a heat pump, a defrosting cycle is performed
periodically (as described in detail below) in order
to melt a layer of frost deposited on an outside
surface of the battery 130. In particular, the
operation of the system 100 is reversed, so that the
outside battery 130 (acting as a condenser) is
heated, melting the frost. Alternatively, the
operation of the heat-pump system 100 is interrupted
and the frost is melted by electrical heating, by a
flow of air or of water at a suitable temperature,
or by the injection of hot gas coming from inside
the outside battery.
With reference now to Figure 2, a method 200 of
controlling the defrosting cycles in the heat-pump
system described above, starts in box 203, in which
the system is activated, for example, when it is
switched on, when it leaves a stand-by state, or
when it starts up again after a thermostatic
intervention to regulate the temperature of the
inside environment. Going on to box 206, a
parameter STh which represents a threshold
temperature for the implementation of the defrosting
cycle is set at a predetermined initial (default)
value, for example, equal to a few degrees
centigrade below zero, such as -2°C. A parameter
TWait, which represents a minimum waiting time between
two consecutive defrosting cycles or between the
activation of the system and a first defrosting
cycle (used for limiting the repetition of the
defrosting cycles with regard to time) is preferably
set at a further predetermined initial value, for
example, of a few minutes, such as 15 minutes. It
should be noted that, in general, the time is
measured in relation to the operation of the heat-pump
system, for example, as the period of operation
of the compressor.
Going on to box 207, the value S of the
temperature measured by the defrosting probe is then
acquired. In box 209, the method checks whether a
first defrosting cycle has been carried out since
the heat-pump system was activated; this preferably
enables the parameters (STh and TWait) of the system to
be modified only after this first defrosting cycle.
If the answer is negative, the method goes on to box
212 (described below). If the answer is
affirmative, the method checks, in box 215, whether
the operating time TD which has elapsed since the
last defrosting cycle exceeds a predetermined
minimum value, for example, of a few minutes, such
as 10 minutes; the system parameters are preferably
modified only after this operating period, so as to
allow the system to reach a steady state. If the
answer is negative, the method goes directly to box
212. If the operating time TD since the last
defrosting cycle is greater than 10 minutes, the
method according to the present invention calculates
a value correlated with a maximum value of the
measured temperature S. In a preferred embodiment,
an average value of the measured temperatures S is
calculated periodically for this purpose. For
example, in the box 221, an average value SAve of the
temperatures S measured since a last modification
cycle is updated. The method then goes on to box
223 in which it is checked whether a predetermined
period of time, for example of 1 minute, has elapsed
since a last modification cycle. If the answer is
negative, the method goes directly to box 212. If
1 minute has elapsed since the last modification
cycle, the method then goes on to box 224 in which
it is checked whether the average value SAve is
greater than a maximum temperature value SMax (set
initially at an invalid value). If the answer is
affirmative, in box 227 the value SMax is set at the
average value SAve and the method then goes on to box
230. If the average value SAve is not greater than
the maximum value SMax, the method goes directly to
box 230. With reference now to box 230, the method
according to the present invention modifies the
parameter STh which is representative of the
threshold temperature for performing the defrosting
cycle in dependence on the maximum value SMax; the
parameter STh is preferably set at the maximum value
SMax minus a predetermined value, for example, of a
few degrees centigrade, such as 3°C.
The parameter TWait which is representative of
the minimum waiting time between two consecutive
defrosting cycles is advantageously modified in
dependence on the value of the parameter STh. For
example, in box 233, the method checks whether the
parameter STh is below a predetermined minimum value,
for example, of a few degrees centigrade below zero,
such as -4°C. If the answer is negative, the method
goes directly to box 212. If the parameter STh is
below the minimum value, the parameter TWait is set at
a higher predetermined value, for example, 45
minutes, in box 236. The method then goes on to box
212.
With reference now to box 212, the method
checks whether a defrosting cycle is in operation.
If not, the method goes to box 239 in which it is
checked whether the measured temperature S is below
the parameter STh and whether the time TD since the
last defrosting cycle (or since the activation of
the system) is greater than the parameter TWait. If
at least one of these conditions is not satisfied,
the method goes to box 242 (described below). If,
on the other hand, both of the conditions are
satisfied, the method goes to box 245 in which a
defrosting cycle is started, for example, by the
reversal of the operation of the heat-pump system;
if this is the first defrosting cycle, the parameter
TWait is also modified, preferably to a predetermined
value, for example, of 30 minutes, between the
initial value (15 minutes) and the value set in box
236 (45 minutes). The method then goes to box 242.
Returning to box 212, if a defrosting cycle is
in progress, the method preferably controls the
duration of this operation. For example, in box
248 it is checked whether a predetermined minimum
time TMin, for example, of 2.5 minutes, has elapsed
since the start of the defrosting cycle. In
general, it is in fact preferable for the defrosting
cycle to have a minimum duration since excessively
frequent reversals of the operation of the heat-pump
system may cause excessive leakage of oil in the
compressor with consequent damage to the system. If
the minimum defrosting time TMin has not elapsed, the
method goes directly to box 242. Otherwise, the
method goes to box 251 in which it is checked
whether the measured temperature S is greater than
a predetermined maximum end of defrosting
temperature SEnd, for example, of a few tens of
degrees centigrade, such as 20°C, or whether a
predetermined maximum time TMax, for example, of 6
minutes, has elapsed since the start of the
defrosting cycle. If at least one of these
conditions is satisfied, the defrosting cycle is
terminated in box 253 and the method then goes to
box 242. If neither of the conditions is satisfied,
however, the method goes directly to box 242.
With reference now to box 242, the method
preferably checks whether the time TD which has
elapsed since the last defrosting cycle is greater
than a predetermined maximum value, for example of
a few tens of minutes, such as 90 minutes. If not,
the method returns to box 207 in order to repeat the
steps described above. If a longer time has
elapsed, however, the method goes back to box 206 so
as to reset the initial values of the parameters of
the system.
Naturally, in order to satisfy contingent and
specific requirements, an expert in the art may
apply to the above-described method of controlling
the defrosting cycles in a heat-pump system many
modifications and variations, all of which, however,
are included within the scope of protection of the
invention as defined by the following claims.
Claims (15)
- A method (200) of controlling the defrosting cycles of a battery (130) in a heat-pump system (100), comprising the steps of:detecting (207) a first value (S) indicative of a state parameter relating to a refrigerant fluid used in the system (100),comparing (239) the first value (S) with a threshold value (STh),performing (245) a defrosting cycle in dependence on a result of the comparison,
characterized by the steps of:determining (221-227) a second value (SMax) correlated with a maximum value of the first value (S),modifying (230) the threshold value (STh) in dependence on the second value (SMax). - A method (200) according to Claim 1, in which the step of determining (221-227) the second value (SMax) includes the steps of:periodically calculating (221, 223) an average value (SAve) of the first value (S),setting (224, 227) the second value (SMax) at a maximum of the average values (SAve).
- A method (200) according to Claim 2 or Claim 3, in which the step of modifying (230) the threshold value (STh) consists in setting the threshold value (STh) at the second value (SMax) minus a first predetermined value.
- A method according to any one of Claims 1 to 3, further comprising the step of setting (206) the threshold value (STh) at an predetermined initial value upon each activation of the system (100).
- A method according to Claim 4, further comprising the step of setting (242, 206) the threshold value (STh) at the predetermined initial value when a period of operation (TD) since a last defrosting cycle is greater than a first predetermined maximum value.
- A method (200) according to any one of Claims 1 to 5, in which the step of modifying (230) the threshold value (STh) is carried out only (209) after a first defrosting cycle after the activation of the system (100).
- A method (200) according to any one of Claims 1 to 6, in which the step of modifying (230) the threshold value (STh) is carried out only (215) when the period of operation (TD) since the last defrosting cycle is greater than a first predetermined minimum value.
- A method according to any one of Claims 1 to 7, in which the defrosting cycle (239, 245) is carried only if, at the same time, the period of operation (TD) since the last defrosting cycle or since the activation of the system (100) is greater than a further threshold value (TWait), the method (200) further comprising the steps of setting (206) the further threshold value (TWait) at a further predetermined initial value each time the system (100) is activated, modifying (245) the further threshold value (TWait) to a second predetermined value greater than the further predetermined initial value after the execution of the first defrosting cycle, and modifying (233, 236) the further threshold value (TWait) to a third predetermined value greater than the second predetermined value when the threshold value (STh) is below a second predetermined minimum value.
- A method according to Claim 8, further comprising the step of setting (242, 206) the further threshold value (TWait) at the further predetermined initial value when the period of operation (TD) since the last defrosting cycle is greater than the first predetermined maximum value.
- A method (200) according to any one of Claims 1 to 9, in which a duration of each defrosting cycle is greater than a third predetermined minimum value (248) and the defrosting cycle is terminated (253) when the first value (S) exceeds a second predetermined maximum value or the duration exceeds a third predetermined maximum value (251).
- A method (200) according to any one of Claims 1 to 10, in which the step of performing (245) the defrosting cycle consists of the reversal of the operation of the heat-pump system (100) in order to heat the battery (130).
- A method (200) according to any one of Claims 1 to 11 in which the state parameter is a temperature.
- A heat-pump system (100) comprising a battery (130), means (160) for detecting a first value (S) indicative of a state parameter relating to a refrigerant fluid used in the system (100), and logic means (165) for comparing the first value (S) with a threshold value (STh) and performing a cycle for defrosting the battery (130) in dependence on a result of the comparison,
characterized in that it includes:logic means (165) for determining a second value (SMax) correlated with a maximum value of the first value (S) and modifying (230) the threshold value (STh) in dependence on the second value (SMax). - A heat-pump system (100) according to Claim 13, in which the detection means (160) include a temperature transducer disposed in the battery (130).
- A heat-pump system (100) according to Claim 13 or Claim 14, in which the system (100) is an air-conditioner.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE69715835T DE69715835T2 (en) | 1997-07-22 | 1997-07-22 | Control procedure for defrosting in a heat pump system |
| SI9730447T SI0893663T1 (en) | 1997-07-22 | 1997-07-22 | A method for controlling the defrosting cycles in a heat-pump system |
| ES97830379T ES2184054T3 (en) | 1997-07-22 | 1997-07-22 | PROCEDURE FOR THE CONTROL OF DEFROSTING CYCLES IN A HEAT PUMP SYSTEM. |
| PT97830379T PT893663E (en) | 1997-07-22 | 1997-07-22 | METHOD OF CONTROL OF DEFROST CYCLES IN A HEAT PUMP SYSTEM |
| AT97830379T ATE225022T1 (en) | 1997-07-22 | 1997-07-22 | CONTROL METHOD FOR DEFROSTING PROCESSES IN A HEAT PUMP SYSTEM |
| DK97830379T DK0893663T3 (en) | 1997-07-22 | 1997-07-22 | Method for controlling the defrost cycles in a heat pump system |
| EP97830379A EP0893663B1 (en) | 1997-07-22 | 1997-07-22 | A method for controlling the defrosting cycles in a heat-pump system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP97830379A EP0893663B1 (en) | 1997-07-22 | 1997-07-22 | A method for controlling the defrosting cycles in a heat-pump system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0893663A1 true EP0893663A1 (en) | 1999-01-27 |
| EP0893663B1 EP0893663B1 (en) | 2002-09-25 |
Family
ID=8230727
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP97830379A Expired - Lifetime EP0893663B1 (en) | 1997-07-22 | 1997-07-22 | A method for controlling the defrosting cycles in a heat-pump system |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0893663B1 (en) |
| AT (1) | ATE225022T1 (en) |
| DE (1) | DE69715835T2 (en) |
| DK (1) | DK0893663T3 (en) |
| ES (1) | ES2184054T3 (en) |
| PT (1) | PT893663E (en) |
| SI (1) | SI0893663T1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1225406A3 (en) * | 2001-01-18 | 2003-11-26 | JTL Systems Limited | Defrost control method and apparatus |
| EP2426436A1 (en) | 2010-09-07 | 2012-03-07 | AERMEC S.p.A. | Method for controlling the defrosting cycles in a heat pump system and a heat pump system |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4302947A (en) * | 1980-01-04 | 1981-12-01 | Honeywell Inc. | Heat pump system defrost control |
| FR2486217A1 (en) * | 1980-07-04 | 1982-01-08 | Anectron | Defrosting cycle controller for heat pump - uses timer circuits to control power to compressor when evaporator temperature is low |
| US4373349A (en) * | 1981-06-30 | 1983-02-15 | Honeywell Inc. | Heat pump system adaptive defrost control system |
| JPS59189243A (en) * | 1983-04-13 | 1984-10-26 | Matsushita Electric Ind Co Ltd | Defrosting control device of air conditioner |
| JPS6159137A (en) * | 1984-08-28 | 1986-03-26 | Sanyo Electric Co Ltd | Frosting detection method |
| US4790144A (en) * | 1985-11-18 | 1988-12-13 | Matsushita Electric Industrial Co., Ltd. | Defrosting control apparatus for a temperature control system |
| US4882908A (en) * | 1987-07-17 | 1989-11-28 | Ranco Incorporated | Demand defrost control method and apparatus |
| US4887436A (en) * | 1987-11-18 | 1989-12-19 | Mitsubishi Denki Kabushiki Kaisha | Defrosting system for a heat exchanger |
| US5507154A (en) * | 1994-07-01 | 1996-04-16 | Ranco Incorporated Of Delaware | Self-calibrating defrost controller |
| US5515689A (en) * | 1994-03-30 | 1996-05-14 | Gas Research Institute | Defrosting heat pumps |
-
1997
- 1997-07-22 DE DE69715835T patent/DE69715835T2/en not_active Expired - Fee Related
- 1997-07-22 AT AT97830379T patent/ATE225022T1/en not_active IP Right Cessation
- 1997-07-22 ES ES97830379T patent/ES2184054T3/en not_active Expired - Lifetime
- 1997-07-22 SI SI9730447T patent/SI0893663T1/en unknown
- 1997-07-22 PT PT97830379T patent/PT893663E/en unknown
- 1997-07-22 EP EP97830379A patent/EP0893663B1/en not_active Expired - Lifetime
- 1997-07-22 DK DK97830379T patent/DK0893663T3/en active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4302947A (en) * | 1980-01-04 | 1981-12-01 | Honeywell Inc. | Heat pump system defrost control |
| FR2486217A1 (en) * | 1980-07-04 | 1982-01-08 | Anectron | Defrosting cycle controller for heat pump - uses timer circuits to control power to compressor when evaporator temperature is low |
| US4373349A (en) * | 1981-06-30 | 1983-02-15 | Honeywell Inc. | Heat pump system adaptive defrost control system |
| JPS59189243A (en) * | 1983-04-13 | 1984-10-26 | Matsushita Electric Ind Co Ltd | Defrosting control device of air conditioner |
| JPS6159137A (en) * | 1984-08-28 | 1986-03-26 | Sanyo Electric Co Ltd | Frosting detection method |
| US4790144A (en) * | 1985-11-18 | 1988-12-13 | Matsushita Electric Industrial Co., Ltd. | Defrosting control apparatus for a temperature control system |
| US4882908A (en) * | 1987-07-17 | 1989-11-28 | Ranco Incorporated | Demand defrost control method and apparatus |
| US4887436A (en) * | 1987-11-18 | 1989-12-19 | Mitsubishi Denki Kabushiki Kaisha | Defrosting system for a heat exchanger |
| US5515689A (en) * | 1994-03-30 | 1996-05-14 | Gas Research Institute | Defrosting heat pumps |
| US5507154A (en) * | 1994-07-01 | 1996-04-16 | Ranco Incorporated Of Delaware | Self-calibrating defrost controller |
Non-Patent Citations (2)
| Title |
|---|
| PATENT ABSTRACTS OF JAPAN vol. 009, no. 055 (M - 362) 9 March 1985 (1985-03-09) * |
| PATENT ABSTRACTS OF JAPAN vol. 010, no. 222 (M - 504) 2 August 1986 (1986-08-02) * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6718778B2 (en) | 2001-01-16 | 2004-04-13 | Jtl Systems Limited | Defrost control method and apparatus |
| EP1225406A3 (en) * | 2001-01-18 | 2003-11-26 | JTL Systems Limited | Defrost control method and apparatus |
| EP2426436A1 (en) | 2010-09-07 | 2012-03-07 | AERMEC S.p.A. | Method for controlling the defrosting cycles in a heat pump system and a heat pump system |
Also Published As
| Publication number | Publication date |
|---|---|
| DE69715835D1 (en) | 2002-10-31 |
| SI0893663T1 (en) | 2003-04-30 |
| DK0893663T3 (en) | 2002-10-28 |
| ATE225022T1 (en) | 2002-10-15 |
| ES2184054T3 (en) | 2003-04-01 |
| EP0893663B1 (en) | 2002-09-25 |
| DE69715835T2 (en) | 2003-05-28 |
| PT893663E (en) | 2003-01-31 |
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