DE102007055608A1 - Combined air-conditioning installation and refrigerating circuit for air-conditioning a vehicle's interior has a first refrigerant with a Rankine circuit and a second refrigerant - Google Patents

Abstract

An air-conditioning refrigerating circuit (10) and a Rankine refrigerating circuit (20) have a section, over which heat is exchanged between a third medium and the air-conditioning refrigerating circuit along with the Rankine refrigerating circuit. In this section, refrigerants flow from both these circuits in the same parallel direction and adjacent to each other.

Description

The The invention relates to a combination of a refrigeration cycle for air conditioning a vehicle interior with a Rankine cycle according to the preamble of claim 1.

in the Clausius Rankine process first becomes water in a closed cycle evaporated in an evaporator and possibly superheated, causing the pressure increases. In a subsequent step in a turbine (or a working cylinder or similar) The steam is released and then in a condenser again liquefied. The upheaval the water takes place with the help of a pump. As part of the process the following state changes take place: 1. Isobaric heat supply in the evaporator, taking the water first to the evaporation point heated evaporated and then overheated becomes. 2. Adiabatic expansion of the steam in the turbine. 3. Isobars and isothermal condensation of the vapor in the condenser. 4. Adiabatic, isentropic pressure increase through the pump.

Becomes instead of water another working fluid used, so called one this process as Organic Rankine process or Organic Rankine Cycle (ORC).

From the DE 10 2005 047 760 A1 For example, a complex fluid machine comprising a compressor apparatus for a refrigeration cycle and a Rankine cycle expansion apparatus for collecting waste heat from an engine having an engine cooling water circuit and converting it to a rotational force is known. Here, the evaporator of the engine cooling water circuit forms the heating device for the Rankine cycle. The thus recovered, converted in the Clausius-Rankine cycle through the expansion device energy is used to drive the compressor device, which circulates the cooling circuit.

A simple Clausius-Rankine cycle, which uses the heat of the exhaust gas of an internal combustion engine directly, is from the US 4,406,127 A known. In this case, water is removed from a water reservoir by means of a pump and sprayed onto the exhaust of the engine, so that it evaporates. The evaporated water is passed through a throttle and cylinder. If necessary, it is subsequently cooled in a condenser before being returned to the water reservoir.

The DE 28 48 532 A1 discloses a Clausius Rankine cycle, the energy recovered from waste heat is used to circulate the refrigerant of an air conditioner.

outgoing From this prior art, it is an object of the invention, a Combination of a cold cycle for the air conditioning of a vehicle interior with a Rankine cycle improved to improve. This task is solved by a combination of a refrigeration cycle for air conditioning a vehicle interior with a Rankine cycle with the features of the claim 1. Advantageous embodiments are the subject of the dependent claims.

According to the invention is a Combination of an air-conditioning refrigeration cycle for the air conditioning of a vehicle interior, containing a first Refrigerant with a Rankine cycle containing a second refrigerant, provided, wherein the two circuits at least one leg have, over which is a heat exchange the two refrigerants is provided with a third medium, and that in the leg the refrigerants from the two circuits in the same direction parallel and adjacent to each other. Thereby, that the section in which the heat exchange takes place, common for the two circuits can be used, the existing heat transfer surface optimally be exploited, even if possibly only a circuit or branch is in operation.

According to one preferred embodiment for both cycles the same refrigerant, particularly preferably R134a, provided. This may be preferred a refrigerant exchange between the two circuits be provided.

Of the Refrigerant exchange the two circuits takes place preferably in the region of a jointly flowed through section the circuits, the most preferred by at least one common capacitor is formed. It does not necessarily have the entire capacitor form the common leg. It is rather possible, one Circulation at a further downstream Point of the condenser open and / or a circuit at a further opposite to the direction of flow point to divert the capacitor. However, the preferred entire condenser flows through the entire refrigerant flow, so that a conventional capacitor is used can be. Adjustments to the two circuits are only in the area the connecting cables required. Furthermore, the whole of the fan of the Also use capacitor applied blowing surface, even if only one of the circuits is operated. The temperature level of the refrigerant in the condenser is in this case, sufficiently high, to the heat of condensation with a relatively small fan power be discharged to the ambient air.

In the common section can also be a common collector and / or ge be provided common subcooling. The merging of the areas reduces the required number of components and thus the costs, as well as the total weight.

alternative to a mixing of the refrigerant the two circuits in a shared leg, the leg is through a shared capacitor with parallel lines formed, which for a heat exchange with the same of a shared medium, in particular Air, can be flowed through. Here, the lines are preferably in the flow direction of the common used medium arranged one behind the other. Between the lines, the heat transfer surface magnifying structures, as in particular corrugated fins, be provided.

Prefers is provided in the Rankine cycle an evaporator, which from the Engine-derived heat to the refrigerant of the Rankine cycle transmits. Becomes the heat over that Transfer engine coolant, so can increase the efficiency of the control temperature of the engine cooling circuit elevated especially on over 100 ° C and especially preferred over 110 ° C. In spite of the heightened Temperature in the evaporator are the refrigerant temperatures in the Rankine cycle when using R134a below the decomposition temperature of Refrigerant. The same applies to the use of other commercially available refrigerant and lubricating oils.

The in the circuits flowing refrigerant preferably reaches a supercritical in one area of the one cycle State while it is not supercritical in the other cycle under normal operating conditions State reached.

Especially preferred is the use of R134a or a refrigerant with similar ones thermodynamic properties as refrigerant in the Rankine cycle and / or in the air conditioning refrigeration cycle. Such a refrigerant is especially good for the use of a scroll expander in the Rankine cycle suitable because in the usual Refrigerant flows the Expansion volume flow good to the displacement and speed range of the from scroll compressors derived expander fits, so that no Special constructions for the expander are required and thus the costs are reduced can.

in the Below, the invention with reference to two embodiments with reference explained in detail on the drawing. Show it:

1 1 is a schematic view of a combination of a refrigeration cycle for air conditioning a vehicle interior with a Rankine cycle according to the first embodiment;

2 a pressure-enthalpy diagram (ph diagram) for R134a with schematically drawn processes of the Organic Rankine cycle and a refrigerant circuit, as provided according to the first embodiment,

3 a temperature-enthalpy diagram (Th diagram) for R134a with sufficient back-condensation of the working fluid R134a,

4 a schematic view of a refrigeration cycle for the air conditioning of a vehicle interior with a Rankine cycle according to the second embodiment, and

5a and 5b schematic representations of examples of the thermal coupling in the region of the capacitors of the two circuits, as provided according to the first or second embodiment.

An air conditioning refrigeration cycle 10 , which is used for the air conditioning of a vehicle interior, has a compressor 11 , a subsequently arranged capacitor 12 with integrated collector 13 and subcooling line 14 , an expansion organ 15 and an evaporator to be supplied by the air to be supplied to the vehicle interior 16 on. The refrigerant used here is R134a, which in the subcritical state is the refrigeration cycle 10 flows through.

To recover excess energy, in this case from the engine cooling circuit of an internal combustion engine (not shown), is an Organic Rankine cycle 20 provided by an electrically driven pump 21 is circulated. The refrigerant of the ORC cycle 20 , also R134a, is powered by the ORC pump 21 to an ORC evaporator 22 in which the refrigerant is vaporized and overheated, for which said excess energy from the engine cooling circuit, in this case transmitted by the engine coolant, is used. The evaporator 22 is flowed through in countercurrent operation, wherein the heat transfer takes place in this case in one stage. However, alternatively, a multi-stage heat transfer is possible.

In order to provide a sufficient temperature difference between the engine coolant and refrigerant, the present invention uses a coolant with an increased glycol content and an overpressure system in the engine cooling circuit, wherein a control temperature of the thermostat controlling the engine cooling circuit of presently 110 ° C. Preferred control temperatures are above 100 ° C, in particular over 110 ° C. Instead of water as a coolant, other liquid media suitable for cooling the engine may be used.

Then to the ORC evaporator 22 becomes the superheated steam of the ORC cycle 20 in an ORC expander 23 relaxed, with the energy gained by a generator 23 ' is driven. The transmission is mechanical, the power or the load torque of the generator 23 ' is controllable. With the ORC expander 23 this is a volume expansion machine, namely a scroll expander, which has a volume expansion ratio of 3.0. Preferred volume expansion ratios of such scroll expanders are between 1.5 and 5.0, more preferably between 2.0 and 3.5.

The steam subsequently passes to the expander 23 for recondensation in an ORC condenser 24 with collector 25 and subcooling line 26 ,

Here are the two cycles 10 and 20 in the area of the capacitor 12 or 24 including collector 13 or 25 and subcooling line 14 or 26 merged, ie the components are only simply present, as a result of merging a mixing of the refrigerant connected to a temperature and pressure compensation takes place. For this reason, the corresponding components in the drawing and hereinafter by the reference numerals 12 / 24 . 13 / 25 respectively. 14 / 26 designated.

A diagram with a representation of the pressure p over the enthalpy h for the two cycles 10 and 20 shows 2 , As a result of following the branching in the ORC cycle 20 arranged pump 21 increases the pressure of the supercooled refrigerant, while in the other branch as a result of the subsequently arranged expansion element 15 the pressure lowers, while in both branches the enthalpy remains substantially constant. In the evaporators arranged below 16 respectively. 22 the enthalpy increases at a substantially constant pressure. Subsequently, by the compressor 11 in the air-conditioning refrigeration cycle 10 the pressure increases at a substantially constant temperature while in the ORC cycle 20 the pressure at substantially constant temperature in the ORC expander 23 decreases. In this case, the regulation takes place in such a way that the pressure in the area of the coincidence of the two branches is approximately the same. As from the presentation of 2 As can be seen, the air conditioning refrigeration cycle works 10 essentially in the subcritical region, during the ORC cycle 20 leave this area.

At the condenser 12 / 24 It is according to the first embodiment, essentially a conventional air-cooled radiator, as it is usually used for cooling the refrigeration cycle of an air conditioner.

According to the second, in 4 illustrated embodiment corresponds to the basic structure of the circuits 10 and 20 that of the first embodiment, unless explicitly mentioned below. In contrast to the first embodiment, however, no refrigerant exchange between the two circuits 10 and 20 provided, that is, the jointly flowed through capacitor 12 / 24 is eliminated and is through a capacitor 12 and a capacitor 24 replaced, which are flowed through parallel to each other by the refrigerant and are further arranged in the same air flow. In the present case form the capacitors 12 and 24 a structural unit (see 5a ), wherein parallel closely juxtaposed but separately formed lines 12 ' and 24 ' in the form of flat tubes for the two refrigeration circuits 10 . 20 are provided. Between the flat tubes common world ribs are provided, so that the lines 12 ' and 24 ' thermally coupled together.

According to a variant with regard to the configuration of the lines 12 ' . 24 ' can, as in 5b Also shown, a shared flat tube with multi-chamber profile can be used, reducing the thermal coupling between the two lines 12 ' . 24 ' is improved. Here, a part of the chambers of the refrigerant of the air conditioning refrigeration cycle 10 and the other part of the chambers from the refrigerant of the ORC circuit 20 flows through. Also in this case, a common corrugated fin can be provided.

Subsequent to the presently designed as a structural unit, shared capacitor flow through the separate refrigerant flows separately formed collector 13 . 25 , The further construction of the refrigeration circuits 10 . 20 corresponds to that of the first embodiment, so that will not be discussed again. Both collectors could also form a unit with a combined capacitor, downstream subcooling sections are formed downstream.

Due to the separation of the two circuits with respect to the refrigerants may be different refrigerants for the air conditioning refrigeration cycle 10 and the ORC cycle 20 be used. Likewise, significantly differing pressures in the circuits 10 and 20 available. Due to the thermal coupling, however, the condensation takes place essentially at the same temperature level.

The control of preferably in both embodiments electrically driven pump 21 of the ORC cycle 20 can depend on the Delivery rate. Alternatively, a regulation in dependence of a predetermined pressure difference or a defined pressure ratio, a predetermined refrigerant temperature after the (last) heating stage of the evaporator 22 or a predetermined density ratio before and after the expander 23 possible.

The delivery rate of the pump 21 as well as the tapped power of the generator 23 ' be regulated according to both embodiments described above, on the one hand, the density ratio of the expander 23 applied refrigerant not more than 50%, in particular not more than 20%, of the volume expansion ratio of the expander 23 differs. In order to increase the amount of heat that can be emitted in the condenser to the ambient air flowing through it in both exemplary embodiments, the pump becomes 21 and the expander 23 in the corresponding ORC cycle 20 regulated such that in the expanded state after the expander, the refrigerant still has a defined overheating.

The refrigerant can also be a work tool. The refrigerant is particular R134a, R152a, CO2, Blend H or similar.

Claims (12)

Combination of an air-conditioning refrigeration cycle ( 10 ) for air conditioning a vehicle interior, containing a first refrigerant, with a Rankine cycle ( 20 ), containing a second refrigerant, characterized in that the two circuits ( 10 . 20 ) have at least a partial section, via which a heat exchange of the two refrigerants with a third medium is provided, and that in the partial section, the refrigerant from the two circuits ( 10 . 20 ) in the same direction parallel and adjacent to each other. Combination according to claim 1, characterized in that both circuits ( 10 . 20 ) contain the same refrigerant, and a refrigerant exchange between the two circuits ( 10 . 20 ) is provided. Combination according to claim 2, characterized in that the refrigerant exchange of the two circuits ( 10 . 20 ) in the region of a jointly flowed through section of the circuits ( 10 . 20 ) he follows. Combination according to Claim 3, characterized in that at least one common capacitor ( 12 / 24 ) for the two circuits ( 10 . 20 ) is arranged, or the common section runs at least in a partially co-flowing condenser. Combination according to claim 3 or 4, characterized in that a common collector ( 13 / 25 ) is provided. Combination according to one of claims 3 to 5, characterized in that a common subcooling path ( 14 / 26 ) is provided. Combination according to Claim 1, characterized in that the sub-section is formed by a shared capacitor ( 12 . 24 ) is formed with parallel lines, which for a heat exchange with the same of a shared medium, in particular air, can flow. Combination according to one of the preceding claims, characterized in that in the Rankine cycle ( 20 ) an evaporator ( 22 ), which is derived from the engine heat to the refrigerant of the Rankine cycle ( 20 ) transmits. Combination according to one of the preceding claims, characterized in that in the circuits ( 10 . 20 ) flowing refrigerant in an area of one of the circuits ( 20 ) reaches a supercritical state while in the other circuit ( 10 ) does not reach a supercritical state under normal operating conditions. Combination according to one of the preceding claims, characterized in that R134a is used as refrigerant in the ORC cycle ( 20 ) serves. Combination according to one of the preceding claims, characterized in that R134a is used as refrigerant in the air-conditioning refrigeration cycle ( 10 ) serves. Combination according to one of the preceding claims, characterized in that the two circuits ( 10 . 20 ) independently of one another or at least in the non-jointly passable subsection independently of each other via pumps ( 11 . 21 ) in each of the circuits ( 10 respectively. 20 ) are provided, are circulatable, wherein operating conditions are provided, in which the Rankine cycle ( 20 ) is at least in the non-jointly flowable section, while the air conditioning refrigeration cycle ( 10 ) is circulated.