U.S. patent application number 13/391286 was filed with the patent office on 2012-06-14 for symmetrical intermediate storage means for heat pumps with cyclical drainage into a main system.
Invention is credited to Michael Loeffler.
Application Number | 20120144853 13/391286 |
Document ID | / |
Family ID | 43628465 |
Filed Date | 2012-06-14 |
United States Patent
Application |
20120144853 |
Kind Code |
A1 |
Loeffler; Michael |
June 14, 2012 |
SYMMETRICAL INTERMEDIATE STORAGE MEANS FOR HEAT PUMPS WITH CYCLICAL
DRAINAGE INTO A MAIN SYSTEM
Abstract
Heat pumps and refrigerating machines operate optimally if the
temperature difference of the connected heat sources and heat sinks
is as small. If this is not the case, there are two negative
effects: At a high spread, increased dissipation occurs in the
condensers and evaporators. In order to increase spread, the heat
return flow is frequently mixed with the heat pump flow. For this
purpose, hydraulic separators and overflow valves are employed.
This results in highly dissipative mixing of heat carrier medium
with differing temperatures. Using a pair of intermediate storage
means, the dissipation that occurs can be drastically reduced. The
low spread of the heat pump is adjusted to the high spread of the
remaining system. The COP of the system is substantially improved.
With heat pumps, the improvement ranges from about 5% to 20%.
Inventors: |
Loeffler; Michael;
(Jockgrim, DE) |
Family ID: |
43628465 |
Appl. No.: |
13/391286 |
Filed: |
August 11, 2010 |
PCT Filed: |
August 11, 2010 |
PCT NO: |
PCT/EP2010/004887 |
371 Date: |
February 19, 2012 |
Current U.S.
Class: |
62/238.7 ;
165/236; 62/325 |
Current CPC
Class: |
F24D 11/0214 20130101;
F25B 2400/24 20130101; F24D 19/1072 20130101; Y02A 40/963 20180101;
F24D 17/02 20130101; F25B 30/00 20130101; F24D 19/1039 20130101;
F24D 19/1054 20130101; Y02A 40/965 20180101 |
Class at
Publication: |
62/238.7 ;
62/325; 165/236 |
International
Class: |
F25B 27/00 20060101
F25B027/00; F24D 11/02 20060101 F24D011/02; F25B 30/02 20060101
F25B030/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 25, 2009 |
DE |
10 2009 039 505.9 |
Claims
1. A set-up of a temperature control system with a heat pump or
refrigerating machine, with a first intermediate storage means, a
second intermediate storage means, valves and a control and with a
remaining system which is supplied with temperature-controlled heat
transfer liquid, characterized in that the two intermediate storage
means can be connected by means of the valves selectively and
alternately to the heat pump or the refrigerating machine or else
to the remaining system.
2. The functioning of a temperature control system with the set-up
as claimed in claim 1, characterized in that the heat
pump/refrigerating machine, in a first stroke, beams the heat
transfer medium in the intermediate storage means 1 to a desired
temperature level, while the intermediate storage means 2
discharges already heated/cooled heat transfer medium to a
remaining system, and the heat pump/refrigerating machine, in a
second stroke, brings the heat transfer medium in the intermediate
storage means 2 to a desired temperature level, while the
intermediate storage means 1 discharges already heated/cooled heat
transfer medium to a remaining system, this then being followed
again by stroke 1 in the case of a heating/cooling demand.
3. The functioning of a temperature control system with a heat pump
as claimed in claim 1, characterized in that the remaining system
contains a heating installation with a store, into which
temperature-controlled heat transfer medium is pumped from the
intermediate storage means, the buffer store of the remaining
system preferably allowing stratified heat storage.
4. The set-up of a temperature control system with a heat pump as
claimed in claim 1, characterized in that the overall system
comprises an installation for service water heating and/or room
heating.
5. The functioning of a temperature control system with a heat pump
as claimed in claim 1, characterized in that the flow passes
through intermediate storage means in opposite directions during
loading and unloading, the loading of the intermediate storage
machines in the case of heat pumps taking place from the top
downward and in the case of refrigerating machines taking place
from the bottom upward.
Description
PRIOR ART
[0001] Heat pumps are at the present time sometimes connected [1,
2, 3] to a buffer store. Depending on the set-up, heating water or
(by means of a heat exchanger) service water can be extracted from
the buffer store. Heat pumps at the present time operate
predominantly with a temperature spread of approximately 5 to 10 K.
Within this spread, the buffer store is brought to a desired
setpoint temperature. It is clear that the overall buffer store, at
the end of a charge phase of the heat pump, is brought to a high
average temperature. The store is fully heated [4].
[0002] FIG. 1 shows the set-up of a conventional heating
installation with a heat pump for service water heating [5]. The
heat pump discharges heat to the service water store by means of
the heat transfer medium and in a heat exchanger which is located
here in the service water store. In this case, the entire store is
heated up cyclically to the level of use. Hot service water can be
extracted in the upper region of the store. In the event of
extraction, cold water flows in in the lower region of the store.
If the heat pump is in operation simultaneously with tapping or if
the water store is partially unloaded, cold water enters the heat
pump and is introduced, only slightly heated, into the upper hot
region of the buffer store. The progressive stratification in the
water store is in this case destroyed during the further charging
operation. In this case, exergy is nullified, and the system work
coefficient falls.
[0003] Recently, intermediate storage means have been proposed
which allow a relatively mix-free charging operation of the store
[6, 7]. These systems have solved the following problems: [0004] 1.
In the introduction of layering into a service water store, the
heated water regions are not intermixed with the colder water
layers. Exergy nullification occurs to a greatly reduced extent.
[0005] 2. The heating operation, that is to say until heat storage
medium at a useful temperature level is available again in the
upper part of the buffer store after tapping, is very short. [0006]
3. Normally cold heat transfer medium is located in the lower part
of the buffer store. When the buffer store is in bivalent operation
in conjunction with other energy generation installations, such as
condensing boilers or a solar installation, this state has a
positive effect upon the system efficiencies of said subsystems.
[0007] 4. The buffer store can be operated at a low mean
temperature without loss of comfort, this leading to low heat
losses due to the heat insulation of the buffer store. The system
work coefficient can rise overall by 20% to 30%.
[0008] The disadvantage of the systems shown is that, in some of
the systems, colder water is located above warmer water in the
intermediate storage means for short times, and this state may lead
to unwanted and exergy-nullifying, hence disadvantageous
intermixing of the cold and warm water. Systems shown in [5] and
[6], in which intermixing does not occur, have a complicated set-up
and require a multiplicity of valves.
Problems to be Solved
[0009] The object of the invention is to provide a system of a heat
pump and intermediate storage means, the system having a simple
set-up and warmer heat transfer medium always being located above
colder heat transfer medium in the intermediate storage means.
Cyclical Intermediate Storage Means with a Symmetrical Set-Up
[0010] To solve said problem areas, the use of two intermediate
storage means in installations with heat pumps or refrigerating
machines is proposed, the intermediate storage means receiving heat
transfer medium, mostly water. The heat transfer medium is pumped
alternately from intermediate storage means 1 and 2 into the
remaining system, for example a buffer store. During this pumping
operation, cold water is pumped out of the remaining system into
the intermediate storage means.
[0011] While the one store discharges the heat transfer medium to
the remaining system, the contents of the other store are heated by
the heat pump. The temperature spread in the heat pump circuit is
in this case very low and the volume flow is very high in
comparison with the temperature rise and volume flow of the
remaining system. These boundary values are advantageous for the
efficiency of both subsystems.
[0012] The intermediate storage means are arranged such that they
make it possible to control the temperature of the heat transfer
medium located in the intermediate storage means and can discharge
this heat transfer medium into the remaining system after
temperature control. Discharge to the remaining system, for example
into a service water store, thus takes place, as required,
alternately from intermediate storage means 1 and 2. It may be
pointed out expressly here that temperature control also means
cooling, that is to say the invention also applies to the case of
cold generation, in which case the position of the loading and
unloading connection pieces in the event of cooling must be in an
interchanged arrangement, that is to say loading by the
refrigerating machine is arranged at the bottom and unloading into
the remaining system is arranged at the top. In this way it is
ensured that, at any time, colder heat transfer medium is located
beneath warmer heat transfer medium and temperature stratification
remains stable in the intermediate storage means.
Operation of the Systems with Two Symmetrical Intermediate Storage
Means
[0013] If the entire temperature-controlled water is brought from
the intermediate storage means 1 into the remaining system, the
valves are switched again such that the intermediate storage means
1 can be temperature-controlled once again by the heat pump. Care
must be taken to ensure that the store involved are designed such
that loading, storage (advantageously with stratification) and
unloading which are as mix-free as possible are possible. For
example, baffle plates may be used in order to prevent turbulence
and intermixing.
[0014] During the unloading of the intermediate storage means into
the remaining system, heat transfer liquid with the desired
temperature and, in comparison with conventional systems without
intermediate storage means, with a markedly reduced mean volume
flow is transferred. The result of a high temperature and low
volume flow is that: [0015] 1. stratification in the main store,
present if appropriate, is maintained during the operation of the
system [0016] 2. hot heat transfer medium is available even after a
short time [0017] 3. further energy-generating installations in the
system, such as, for example, condensing boilers or solar
installations, can operate with higher efficiency, since cold heat
transfer medium is located in the lower region of the main store,
[0018] 4. the thermal losses of the main store are reduced, [0019]
5. the work coefficient of the system rises by 20% to 30%.
[0020] To make clear the position and function of the intermediate
storage means and of a following system, FIG. 2 illustrates a
heating system with a heat pump and two symmetrical intermediate
storage means for service water heating. Nonreturn valves prevent
intermixing of the two circuits. Controllers and further necessary
components are not depicted in the figures. In systems with heating
tie-up (not depicted), depending on requirements, the intermediate
storage means either is heated up to the desired service water
temperature and then pumped into the service water store or the
intermediate storage means is heated up only to the desired room
heating temperature and then pumped into the heating buffer store.
For this purpose, a regulating unit determines the demand for
service water heating and room heating and controls the
corresponding valves.
[0021] FIG. 3 shows a set-up in which the arrangement of the pipe
lines is optimized. In this set-up, hot water which is located in
the pipe lines from the heat pump to the intermediate storage means
is pumped into the service water store, not mixed with cold water,
as in FIG. 2. Exergy nullification is lowered even further as a
result of this arrangement.
[0022] The proposed intermediate storage means may be integrated
directly into the heat pump in new installations. However, retrofit
kits for old installations are also commercially available.
Advantageous forms of construction of the intermediate storage
means, valve regulations and other structural aspects have already
been described in [6] and [7]. The regulation of the valve
changeover arises logically from the functioning of the system.
Literature
[0023] [1] Schraps, Stella: Kombinierter Einsatz von
Elektrowarmepumpe and Solarkollektore in Wohngebauden [Combined use
of electric heat pump and solar collector in residential buildings,
VDI Fortschrittsberichte, series 6, No. 452, page 97. [2]
http://www.geothermie.de/download/WAERMEPU.PDF [3] Karl Ochsner:
Warmepumpen in der Heizungstechnik [Heat pumps in heating
technology], 4th edition, C. F. Muller Verlag, Heidelberg, 2007 [4]
bine project info 14/01, p. 2f,
http://www.bine.info/pdf/publikation/bi1401.pdf
[5] Kiril Popovski, Sanja Popovska Vasilevska, IGD2001,
17.-22.09.2001
[0024] [6] Loffler, Michael: Speicher fur Warmepumpen mit
zyklischer Entleerung in ein Hauptsystem [Store for heat pumps with
cyclical drainage into a main system], KI 12/2008 [7] Loffler,
Michael: Getakteter Betrieb bei Heizsystemen mit Warmepumpe
[Clocked operation in heating systems with a heat pump], KI
7/2009.
DESCRIPTION OF THE CLAIMS AND FIGURES
[0025] claim 1 describes the basic use of two symmetrically
arranged intermediate storage means in conjunction with a heat pump
for controlling the temperature of a heat transfer medium and for
conveying the temperature-controlled heat transfer medium into a
remaining system which in most cases is a heating installation.
[0026] Claim 2 contains a temperature control system with a heat
pump and two intermediate storage means, the temperature-controlled
medium being pumped into a buffer store after temperature control,
the buffer store advantageously allowing temperature
stratification.
[0027] Claim 3 relates to a system with a heat pump and
intermediate storage means, the heated heat transfer medium being
pumped after heating from an intermediate storage means into a
service water store, heating store or combined store. This system
serves for supplying heat to buildings and, if appropriate, for
supplying hot service water.
[0028] Claim 4 relates to the throughflow direction in the
intermediate storage means. The flow passes through the
intermediate storage means from the top downward during the loading
of these and from the bottom upward during unloading. This takes
place conversely in the case of operation with a refrigerating
machine, that is to say from the bottom upward during the loading
of the intermediate storage means with cold heat transfer liquid
and from the top downward during unloading to the remaining
system.
[0029] FIG. 1 shows the set-up of a conventional heating system for
service water heating with the heat pump. The heat pump heats the
heat transfer medium. The heat transfer medium discharges the heat
to the service water by means of a heat exchanger which is located
here in the service water store. In this case, the entire store is
heated up to the level of use. Hot water can be extracted in the
upper region of the store. In the event of extraction, cold water
flows in in the lower region of the store.
[0030] FIG. 2 shows the set-up of a heating system according to the
invention with the heat pump and two intermediate storage means. In
a first stroke, V1 and V3 are opened and V2 and V4 are closed. The
intermediate storage means 1 is loaded via the heat pump with a
high volume flow and a low spread. At the same time, the
intermediate storage means 2 is unloaded into the main store with a
low volume flow, cold water flowing from the main store back into
the intermediate storage means 2 via nonreturn valve R2. In the
second stroke, V2 and V4 are opened and V1 and V3 are closed. The
role of the intermediate storage means is thereby interchanged:
intermediate storage means 1 is then unloaded and the intermediate
storage means 2 is loaded.
[0031] FIG. 3 shows basically the same set-up as in FIG. 2, the
pipe routing being optimized. Hot water which is located between
the heat pump and intermediate storage means is pumped into the
buffer store during the changeover of valves in FIG. 3. In FIG. 2,
the hot water is, by contrast, intermixed with cold water, this
corresponding to exergy nullification, albeit low.
[0032] FIG. 4 shows the set-up of a system for service water
heating with a heat exchanger WT. The heated water from the
intermediate storage means discharges its heat to the drinking
water via a heat exchanger WT. In the set-up, a further water pump
P3 is required on account of the drinking water circuit. The heat
exchanger WT operates with very high efficiency on account of the
low volume flow.
* * * * *
References