HYBRID COMMERCIAL VEHICLE (HCV) DELIVERABLE · PDF fileHYBRID COMMERCIAL VEHICLE (HCV)...

Responsible (Name, Organisation) Walter Ferraris, CRF

DELIVERABLE REPORT

Page

1(30)

Issuer (Name, Organisation)

Walter Ferraris, CRF

Tytus Adamczewski, SOLARIS

Date

April 2013

WP No

2200

Report No

D2200.1

Subject:

Technology evaluation report for auxiliaries for e-A/C, e-compressor and e-heating

Dissem. Level

PU

HYBRID COMMERCIAL VEHICLE (HCV)

DELIVERABLE D2200.1

TECHNOLOGY EVALUATION REPORT FOR AUXILIARIES FOR e-A/C, e-COMPRESSOR

AND e-HEATING

HCV Hybrid Commercial Vehicle – D2200.1, Rev_0 page 2 of 30

Summary In this document the significant activity regarding the WP2200 (Task 2210) will be described. CRF and Solaris are involved in the investigations on the electric A/C system, electric air compressor and electric heating in order to define the HCV project improvements for these components. The target is to update and complete the know-how in order to have the right tools and the right competences to project a more efficient system.

Conclusion The technical scenario proposed in this document shows some of the most promising solutions and components for high efficiency e-A/C, e-Compressor and e-Heating systems focused on the new traction vehicles application. This is a good starting point for the auxiliary systems that will be developed in the HCV project for the hybrid vehicle. In the Task 2220 we will evaluate all the best component solutions by model and simulation in order to define the most efficient solution to implement in the prototypes.


Table of content Summary ............................................................................................................................... 2

Conclusion ............................................................................................................................ 2

Table of content..................................................................................................................... 3

Table of figures ..................................................................................................................... 4

List of Tables ......................................................................................................................... 4

1 Electrical Air Conditioning .............................................................................................. 5

1.1 Introduction ............................................................................................................. 5

1.2 A/C Compressor for hybrid and electric vehicle ....................................................... 5

1.2.1 DENSO solution ............................................................................................... 5

1.2.2 SANDEN solution ............................................................................................. 7

1.2.3 DELPHI Solution .............................................................................................10

1.3 Plant Solution .........................................................................................................12

1.3.1 Intermediate Heat Exchanger ..........................................................................12

1.3.2 Dual loop solutions ..........................................................................................13

1.4 Costs Analysis ........................................................................................................15

2 Electrical air compressor ..............................................................................................17

2.1 Technology description & evaluation ......................................................................17

2.2 Technology description & evaluation ......................................................................20

2.3 Applied solution HYDROVANE V6T .......................................................................21

2.4 Costs analysis ........................................................................................................22

3 Heating system and air conditioning system in hybrid busses .......................................23

3.1 Air- conditioning system .........................................................................................23

3.2 Water heating system with Grayson electric heating device ...................................24

3.3 Possibility of application of the electric heating system ...........................................25

3.4 Control of heating system components...................................................................29

3.5 Costs analysis ........................................................................................................30


Table of figures Figure 01 – DENSO compressor production chronology ................................................................. 6 Figure 02 – Compressor Comparison .............................................................................................. 6 Figure 03 – Left: SANDEN Hybrid Compressor; Right: The Hybrid compressor scheme .............. 7 Figure 04 – C.O.P comparison under the same Refrigerating Capacity & Technical Info .............. 7 Figure 05 – SANDEN F655 electrical prototype compressor .......................................................... 8 Figure 06 – Refrigerating Capacity and C.O.P. ............................................................................... 9 Figure 07 – C.O.P comparison under the same Refrigerating Capacity ......................................... 9 Figure 08 – Electrical motor, compressor and CAD installation and coupling .............................. 10 Figure 09 – System Architecture .................................................................................................... 10 Figure 10 – GM solution ................................................................................................................. 11 Figure 11 – NP A/C loop with IHX .................................................................................................. 12 Figure 12 – IHX behaviour ............................................................................................................. 13 Figure 13 – Plate brazed water condenser .................................................................................... 14 Figure 14 – Compact Refrigeration Unit ........................................................................................ 14 Figure 15 – Left: Bidirectional expansion valve; Right: Inversion valve ........................................ 15 Figure 16 – Components costs analysis ........................................................................................ 16 Figure 17 – Hydrovane V6T vane – compressor ........................................................................... 21 Figure 18 – Dimension and performance of Hydrovane V6T vane compressor ........................... 22 Figure 19 – Main parts of Hydrovane V6T vane compressor ........................................................ 22 Figure 20 – Grayson heating device .............................................................................................. 24 Figure 21 – Side profile of Grayson heating device ....................................................................... 24 Figure 22 – Heating system of bus with electric heating device .................................................... 25 Figure 23 – PEDRO SANZ electric heater ..................................................................................... 26 Figure 24 – Diagram of connecting the PEDRO SANZ heater ...................................................... 27 Figure 25 – PEDRO SANZ frontbox ............................................................................................... 27 Figure 26 – Heaters arrangement in URBINO HIII 18 ................................................................... 28 Figure 27 – Spheros thermo heater ............................................................................................... 28 Figure 28 – Heating system with CUMMINS ISBe E4 at the rear with AC system. ...................... 30

List of Tables Table 1 - Technical information on the of the compressor and refrigerant circuit ........................... 8

https://teamplace.volvo.com/sites/vtec-HCV/Shared%20Documents/SP1000/Reports_and_deliverables/Deliverable%20review/SP2000/D2200_1-Technology_evaluation-CONFIDENTIAL_SEcomments.doc#_Toc358625938










1 Electrical Air Conditioning

1.1 Introduction

The worldwide scenario of road transport is moving towards a new generation of vehicles with enhanced power train able to guarantee a further increase of the fuel economy.

This is mainly due to the CO2 reduction initiatives and to the change of the world energy economy caused by the rapid increase of the developing countries and the related increase of fossil fuel demand. One of the technical solutions guaranteeing a significant fuel economy improvement is represented by the so-called micro-hybrid power train able to operate the Stop & Start function and, in the most sophisticated version, to recuperate the braking energy. The Stop & Start function allows stopping the engine automatically at car idle condition.

This feature presents a problem because current A/C-compressors would also stop and so the temperature inside the vehicle rises. As hybrid vehicles also have mostly sufficient electrical energy available there is the possibility to run the compressor by an electric motor. Anyway, the hybrid and pure electric traction will be probably the new generation of power train in order to warrant the lower environmental impact.

All the vehicle auxiliaries systems have to be reviewed in order to assure the same performances as the actual production vehicle in terms of comfort and usability, but with a lower power consumption to minimize the impact on vehicle autonomy. In this section we will focus on the A/C system and we will provide an overview on the solutions realized by some car makers which are using hybrid or electrical compressor systems and some innovative solutions on the plant lay-out in order to improve the efficiency. The fuel saving potential of the individual technologies including the pros and cons have been evaluated in the Task 2220 and presented in the deliverable “D2200.2: Detailed specifications of auxiliaries for e-A/C (CRF), e-compressor and e-heating (Solaris)”.

1.2 A/C Compressor for hybrid and electric vehicle

Following the introduction above, we will describe the main solutions adapted in hybrid or electrical vehicles. The main component that has to be reviewed in order to adapt the A/C system on the new alternative traction vehicle is the compressor. Toyota, Honda and some others are using solutions from DENSO, SANDEN and DELPHI described on the following pages.

1.2.1 DENSO solution

DENSO TS started the electrical compressor production in year 1995. Actually DENSO has three compressors with different sizes and component characteristics available. The development chronology is shown in Figure 01.


Figure 01 – DENSO compressor production chronology

The main features of the DENSO compressors are:

integrated Inverter

Inverter cooled directly by suction refrigerant

Oil separator in order to improve the system capacity and the compressor lubrication

CAN communication to simplify the compressor management and diagnostics The three compressors performances are shown and compared in Figure 02.

*note1 : pd/ps = 1.47/0.196MPaG SC = 5°C SH=10°C *note2 : pd/ps = 1.47/0.196MPaGSH=10°C

Figure 02 – Compressor Comparison


The noise measurements are performed with the compressor mounted on rigid bracket and the measurement point is 1m from the side of the compressor.

1.2.2 SANDEN solution

SANDEN has developed some hybrid compressor systems with different sizes and moreover some fully electric compressor.

The hybrid compressor has two compression mechanisms and each compression mechanism is driven independently. One is driven by the engine crankshaft pulley belt and the other by an integrated electrical engine. The scroll compression mechanism, which has superior efficiency, is used for both. Both drives, crankshaft pulley belt and e-engine, are used to accelerate the cool down. E-engine drive is used for idle stop cooling The key factor to minimize packaging volume was to reduce, as small as practicable, both the belt drive and the e-engine drive. A 15 cc electrically driven scroll compressor gives enough performance to keep the passengers comfort level during idle stop condition. A 75 cc belt driven compressor adds enough performance to achieve good pull down results.

Figure 04 – C.O.P comparison under the same Refrigerating Capacity & Technical Info

Voltage from

inverter

Hermetic plate

Scroll on

motor side

Rotor

Stator

Fixed scroll

Scroll on belt driven

side

Belt driven side (75cc) Electric driven side (15cc)

Refrigerant:HFC134a

Oil: Ester

Three-phase connector

Voltage from

inverter

Hermetic plate

Scroll on

motor side

Rotor

Stator

Fixed scroll

Scroll on belt driven

side

Belt driven side (75cc) Electric driven side (15cc)

Refrigerant:HFC134a

Oil: Ester

Three-phase connector

Belt Driven side (75 cc)

Electric Driven side (15 cc)

Model Name

Type

Belt Driven 75 cc/rev

Motor Driven 15 cc/rev

Belt Drive 9000 rpm

Motor Drive 6000 rpm

Belt Drive 12000 rpm

Motor Drive N/A

Refrigerant

Oil

Motor

Mass

HFC - 134a

SE - 10Y

DC Brushless motor

9 Kg

Maximun

allowable

Displacement

Maximun down

shift speed

HBC75115

2 Scroll Hybrid

Model Name

Type

Belt Driven 75 cc/rev

Motor Driven 15 cc/rev

Belt Drive 9000 rpm

Motor Drive 6000 rpm

Belt Drive 12000 rpm

Motor Drive N/A

Refrigerant

Oil

Motor

Mass

HFC - 134a

SE - 10Y

DC Brushless motor

9 Kg

Maximun

allowable

Displacement

Maximun down

shift speed

HBC75115

2 Scroll Hybrid

Figure 03 – Left: SANDEN Hybrid Compressor; Right: The Hybrid compressor scheme


SANDEN has also developed a fully electric compressor. At the moment the system is in prototype phase, but in the next months the production of an evolution of this component will be started. The main prototype data is shown in the Table 1 and figures: Figure 05, Figure 06, Figure 07.

Table 1 - Technical information on the of the compressor and refrigerant circuit

Motor DC Brush-less

Displacement 27cc/rev

Max. Speed 8500rpm

Refrigerating Capacity Please refer below graph.

Rated Voltage Range 300V to 400 V

Refrigerant / Oil HFC134a / SE-10

Mechanical Dim WxHxD [mm] 222x120x120

Mass 7.6kg (include oil 0.15kg)

The compressor, similar to the model produced by DENSO, is equipped with an internal inverter. The inverter basic functions are:

- Motor speed control – By detecting the rotor magnet position with sensor-less method, compressor speed will be controlled to the target speed indicated by the vehicle ECU.

- CAN communication o Target speed, comp. ON/OFF signal from vehicle ECU o Power consumption, comp. actual speed, failure mode detection from motor

driver - Failure mode detection – Failure mode detection of each sensor and overcurrent

protection

Figure 05 – SANDEN F655 electrical prototype compressor


Figure 06 – Refrigerating Capacity and C.O.P.

The performance of the electric SANDEN compressor is shown in Figure 06 and Figure 07. The test conditions utilized in order to perform the component characterization shown in these two figures are:

- Pd / Ps = 13.7 / 2.0 MPa*G - SH / SC = 10 / 5 K

where:

Pd = Discharge pressure

Ps = Suction pressure

SH = Super Heat

SC = Subcooling

Figure 07 – C.O.P comparison under the same Refrigerating Capacity


1.2.3 DELPHI Solution

DELPHI has developed a different system for a particular application. To provide an A/C system for an electric minibus realized for Dubai mission, Delphi has installed a roof unit equipped with a standard belt compressor (DELPHI SP15) driven by an electrical brushless engine.

The electrical engine is a brushless permanent magnet application. It is operated by on/off mode with CAN protocol in order to optimize the energy consumption. The electronic board needed for motor management (operating at 24 volts) is integrated in the electric engine and it is capable to manage supply voltages from 96 up to 700 volts DC. This configuration gives, as final result, a very compact compressor & motor unit, reducing the overall dimensions and weight dramatically. Furthermore it is required for the development of a compressor & motor units family, related to wide range of application: car, minibus, midibus, bus etc… Some other system key factors are:

New electronic expansion valve

Integrated electronic board that gives to the designer the flexibility to optimize the best ratio between A/C cooling performance and energy consumption

Figure 09 – System Architecture

The target vehicle market was Abu Dhabi so the operating condition was:

Max external temperature: 52 °C

Max HR%: 90

Solar load radiation: 1100 W/m2

Figure 08 – Electrical motor, compressor and CAD installation and coupling


The system characteristics are:

Vehicle voltage supply operative range: 260 - 320 volts

Power A/C system supplied by the same vehicle voltage, without inverter

Max energy consumption: 8 KW at 320 volts equivalent to 25 A

Max internal temperature: 27 °C

Weight: less than 160 Kg

Overall Size (WxHxD) : 2030x1280x230 [mm] Some other car makers have used similar solutions as the described here. CRF doesn’t have details about the compressor typology and construction. The information about these solutions has been found in the literature and it’s been included with the same detail level. The major example in 2010 is MY Ford’s hybrid vehicle. The dual scroll compressor, installed until 2009, was changed by an electric belt driven compressor like the used in the Prius vehicle. General Motors has also realized some similar solutions for its hybrid brand as presented on Figure 10.

Figure 10 – GM solution


1.3 Plant Solution

In order to complete the overview of the state of the art solutions regarding the A/C systems some details about the new plant configuration solutions related to the electrical and hybrid electric vehicles are presented in the following paragraphs.

1.3.1 Intermediate Heat Exchanger

In the last years a lot of car makers have started to use the IHX solution as shown in Figure 11 in order to improve the A/C efficiency. In this kind of solution, the low temperature refrigerant gas at the evaporator outlet cools the liquid refrigerant from the condenser outlet, thus performing an internal energy recovery.

The effects of this kind of heat exchanger solution on the thermodynamic cycle are shown in Figure 12. The effects are mainly on the pressures, where the gap between the High Pressure and the Low Pressure is reduced. Providers of this typology of heat exchangers are:

DENSO

DELPHI

TI automotive

MAFLOW The pipe design can be developed in order to fit the other components and to find the best compromise between the pressure drops and the pipe length. Considering that more pipe length is better in terms of efficiency and heat exchanged longer piping is not problematic.

CABIN

REJECTED HEAT

ENGINE BAY

CONDENSER

COMPRESSOR

EXPANSION

DEVICE

Refrigerant

Loop

EVAPORATOR

Figure 11 – NP A/C loop with IHX


Figure 12 – IHX behaviour

1.3.2 Dual loop solutions

The following points summarize the benefits of using dual loop solutions:

Reduce the refrigerant quantity and therefore the possible leakages

Reduce the dimension of the A/C loop

Reduce the space on the front-end

Improve the security with the new refrigerant usage.

Take advantages by the thermal inertia for the START & STOP solutions There are a lot of plant solutions that can be used. In the following paragraphs some details about the most important solutions are shown.

1.3.2.1 Smart Cooling Solution This solution allows removing the condenser from the frontend and all the other air – fluid heat exchangers. Using a low temperature cooling circuit (working temperature around 60 °C) it is possible to supply the refrigeration to all the components that need it. The solution allows re-organizing the engine bay and managing a new solution on the front-end in order to improve the pedestrian collision normative. The new condenser for the A/C loop will be a plate brazed water condenser as shown in Figure 13, which is compact and has the same efficiency as the air side heat exchanger.


A list of currently available suppliers:

Luvata

Onda

Alfa Laval

GEA

Denso

DANA

1.3.2.2 Secondary Loop Solution The secondary loop solution has been developed to limit the coolant volume flow into the engine bay. The refrigerant HFO - 1234yf is chosen by the most important car makers in order to replace the r134a and to respond to the new 2011 Global Warming Potential (GWP) European normative. This fluid has a good GWP, but is flammable. The Secondary Loop solution allows using the refrigerant fluid for the water refrigeration, and manages the cabin air refreshing and dehumidification with an air cooler. Combining the two solutions (Smart Cooling and Secondary loop) it is possible to develop a Compact Refrigeration Unit (CRU) with smaller refrigerant quantity, compact dimension and with all the advantages provided by the two separated solutions.

CHILLER

CONDENSER

AIR COOLER

EXP VASE

EXP VASE

RADIATOR

CMP

PUMP

PUMP

Figure 13 – Plate brazed water condenser

Figure 14 – Compact Refrigeration Unit


1.3.2.3 Heat Pump To complete the scenario, we want to discuss about the possibility to finalize a civil application heat pump (like the heat pump used in the fan coil configuration) which can be used widely in an automotive solution. This idea was born in order to find an efficient solution for the cabin heating and refreshing in the electrical vehicles. With the pure electrical traction there are few heat sources which are able to supply the heat for the cabin heating. Therefore the possibility to perform a thermodynamic cycle inversion in order to use the cabin heat exchanger as a dual function component has been studied:

In summer mode like an evaporator

In winter mode like a condenser In this way it would be possible to realize both functions with one system. The main components needed are the inversion valve and the bidirectional expansion valve (Figure 15) that can be replaced by an orifice solution. These components are actually available for the fan coil systems, but some suppliers (SANDEN and DENSO) are currently developing and investigating a modified version for a car application.

On the other hand there is some optimization of the heat pump systems required due to the following two main problems:

The evaporator icing on the frontend of the vehicle

The fogging in the cabin (when it is used in the heat pump mode there is no dehumidification possibility)

CRF considers the heat pump to be a potentially good solution in order to realize the heating function on the electrical vehicle without any additional electrical heater or booster.

1.4 Costs Analysis

In the first steps of the project, we have also tried to evaluate the costs of each of the components, in order to have an overall cost estimation of the system. Figure 16 shows the component costs of the Heat Pump system compared with a standard production system. It has to be considered that the Heat Pump system has been quoted for a small number of pieces/year (20 - 30 pieces). For this reason the final cost is currently not comparable to a

Figure 15 – Left: Bidirectional expansion valve; Right: Inversion valve


standard production air conditioning system. Anyway the new solutions make an improvement in many aspects:

Heat functionality without an additional system and without any other thermal sources

Possibility to reduce the pipe length and develop a more compact layout in the engine-bay

Possibility to reduce the refrigerant charge with many collateral advantages in terms of leakage and refrigerant cost (1234yf ready)

The Heat Pump system works also when the vehicle is stopped

Figure 16 – Components costs analysis

Legend: CDS = Condenser HT RAD = High Temperature Radiator TXV = Thermostatic eXpansion Valve AC = Air Conditioning

Actual

costs

Technical

description

Cost

source

Prototype

Costs

CDS 26 ONDA 180

HT RAD 20 DENSO 20

Compressor 400 DENSO 1000

Inversion Valve / / RANCO 34

TXV / 10 DANFOSS 39

AC REFRIGERANT 17,5Fiat

HVAC12,5

Total 520,7 1312,5

Component for HCV Project

Components

NP

[€]

Heat Pump

Cost investigation [€]

47,2 27CLIMA PIPES

AUTOCLIMA


2 Electrical air compressor

2.1 Technology description & evaluation

Presently three kinds of air compressors are available: reciprocating compressor, vane compressor and screw compressor. They can be powered either mechanically or electrically. In the first case the power is transmitted from the diesel engine using a V-belt while electrically driven compressors are equipped with a built-in electric motor. This innovative solution has many advantages and is therefore described in this report. The electric vane compressor is also suggested by the hybrid system supplier thus SOLARIS will mainly focus on this solution for further development activities. A review of features, benefits and disadvantages of the air vane compressor is given below:

General

Advantages Benefits

Simple design - easily understood - user friendly

Integrated design

- low noise level - minimal leak points - no air receiver - easier to maintain

Proven technology - total reliability - no unexpected failures

No air receiver - Reduced installation cost

Direct drive (1450 rpm)

Advantages Benefits

No gears, belts or pulleys - minimal maintenance

No drive losses - minimal energy costs

Fewer moving parts and low running speed

- less component stress and generated (wasted) heat

Low noise level - flexibility of location

No radial loads on bearings - no replacement bearing costs

http://en.wikipedia.org/wiki/Reciprocating_compressor


Only one major rotating part

Advantages Benefits

Simple design - designed reliability

Simple to manufacture - accurate and long lasting components

Low noise level (66 dBA)

Advantages Benefits

Allows sitting close to point of use - lower installation cost

No need for special acoustic cover - lower total cost

Lower noise pollution - no noise related complains - productive operator

100% on duty for 100% of time

Advantages Benefits

Continuity of pressure and volume - guaranteed productivity - no time loss

No need to oversize - minimum total cost - more profit

Built-in aftercooler

Advantages Benefits

Deliver air with temperature not more than 10°C above ambient

- size-optimized dryer - lower total cost

Majority of condensate removed before dryer

- less work for dryer

Reduced footprint - less space required


Plain white metal bearings

Advantages Benefits

No specified change period - no replacement cost - no unexpected breakdowns

More tolerant to arduous condition - last longer

Pressurized oil circulation

Advantages Benefits

No mechanical pump - no mechanical pump failures

Consistent oil circulation - optimum oil supply to key areas - total reliability

Immediate oil circulation on start up

- no non lubricated components - long lasting compressor

Less to service - quicker servicing

Option of continuous run control

Advantages Benefits

Compressor can be sized to match needs

- minimal total cost

Constant delivered air pressure - accurate control of process

Less stress on drive components - lower maintenance and repair cost

Best for continuous high demand - minimal energy cost

No need for air receiver - lower installation cost - no inspection downtime

The main disadvantages of vane compressors is their availability (limited number of suppliers), and hence the high price. But on the other hand rotary vane compressors have many advantages as mentioned above and additionally the longest durability while delivering the same air quality as the screw compressors.


2.2 Technology description & evaluation

This chapter gives some information on the comparison of the vane and screw compressors.

Compressor construction

Vane compressor Screw compressor

Integrated - unique - minimal connections - simple - silent as standard

Not-integrated - indistinguishable - many connections - complicated - extra silencing required

Direct drive - no efficiency losses - no replacement costs - reliable - limited noise - less components

Belt/gear drive - increasing efficiency losses - regular replacement costs - unreliable - noisy - more components

Controls


Servo - continuous run - smooth system pressure - no receiver required

Direct control - load / unload - fluctuating system pressure - receiver required

Regulated speed - standard inverter - standard compressor - standard motor - optimum motor cooling

Regulated speed - special technology - high speed air-end - special motor - possible overheating

Life


100 000 hrs life minimum 30 000 hrs life maximum

Plain white metal bearing Roller bearing

Slow speed (1450 rpm) High speed (3000 rpm)

Low stress High stress

Efficiency


113,3 dm3/min 113,3 dm3/min

Lower HP more efficient Higher HP more efficient


Life cost


Similar overhaul costs Similar overhaul costs

Replacement of air-end never required

Replacement of air-end every 30 000 hrs.

Similar energy cost Similar energy cost

Similar regular maintenance cost Similar regular maintenance cost

2.3 Applied solution HYDROVANE V6T

Nowadays electric air compressors (e-compressor) are more often used in the automotive industry. The e-compressor provides air pressure even during “idle” stops (when the engine shuts down to save fuel and emissions). This maintains the functionality of the pneumatic system while reducing fuel consumption. SOLARIS expect that application of the new electric air compressor will reduce the fuel consumption of the bus by ~10% as well as improve the emissions of noxious substances. For the HCV project the electrically driven vane-compressor V6T (Figures 17 and 18) produced by Hydrovane was selected. The selection is based on the benefits of these type of compressor compared to other compressors (especially screw compressor) as described in paragraph 2.1.

Figure 17 – Hydrovane V6T vane – compressor

The main technical data of the proposed e- compressor is presented on the Figure 18 and some information on the main parts of the compressor is shown on Figure 19.


Figure 18 – Dimension and performance of Hydrovane V6T vane compressor

1 – Air filter 2 – Rotor 3 – Slats 4 – Oil separator 5 – Oil cooler 6 – By-pass oil nozzle

Figure 19 – Main parts of Hydrovane V6T vane compressor

2.4 Costs analysis

Costs were calculated for a prototype unit. Because of common use of listed elements the cost is exactly the same as a standard system price.


Component Cost source Prototype costs [€]

E-compressor HYDROVANE V6T TSSP 1640


3 Heating system and air conditioning system in hybrid busses

Air conditioning and heating systems presented in this paragraph concerns the articulated bus “Urbino 18 m” and consist of the following units:

combustion heating device

heaters and convectors

air-conditioned front box

air-conditioned passenger compartment

driver The components presented below were proposed by manufacturer solution for articulated buses and were examined for the purpose of the HCV project. The main reason for proposing this solution were related to low weight of the individual systems compared to other, the sufficient total efficiency and availability on the market in the Central and Eastern Europe. Currently water heating is used in the buses. The liquid is heated up by the components in the engine cooling system and additionally by another heating device (combustion of fuel). From this point the liquid runs to individual receivers, such as:

Pedro Sanz convectors – heating power Q80 - 0,7 kW/1m convector’s length

Aurora Teddy heater (passenger space) – heating power Q80 - 7,2 kW

Air-conditioned frontbox Aurora – heating power Q80 – 16,9 kW

Optional Konvekta roof heating – heating power Q100 – 30 kW Total heating power in the whole vehicle depends on the number of receivers. SOLARIS predicts that fuel consumption with buses contained an electrical heating will be decreased by about 8% and as also emissions of noxious substances will be decreased by about 8%.

3.1 Air- conditioning system

The air conditioning system consists of the device for cooling/heating passenger compartment and driver cabin. The Air Conditioning system Konvekta 2xUL500 is proposed mainly due to the low weight of the UL500 unit of 109 kg. The performance of one unit is not sufficient for articulated bus thus 2 units have been proposed. There is also possibility to use one bigger unit but due to the hybrid installation on the roof there was not enough space to assembly it. Air conditioning system 2xUL500 consists of two units UL500 with BOCK compressor powered by belt transmission in the engine. Konvekta 2xUL500 air-conditioning parameters:

cooling power – 48 kW

heating power – 60 kW

evaporator blower’s rated flow rate – 8640 m3/h

cooling medium – R134a

Aurora air-conditioned frontbox – cooling power 8,4 kW, rated air flow 720 m3/h


Air-conditioning system 2xUL500 is equipped with brushless condenser fans and brushless blower evaporators. Cooled or heated air is distributed evenly in the entire length of the vehicle through air-conditioning ducts, and is blown out above the gangway and side windows.

3.2 Water heating system with Grayson electric heating device

The innovative solution which is proposed by Grayson to be applied for the hybrid bus, is electric heating device instead of a combustion device used as a standard. Developed by Grayson company, a product called Thermal Resistor can be powered by the battery of the vehicle and can be used for heating of the passenger compartment also when the engine is turned off. This provides effective heating of the passenger compartment and the driver cabin, eliminating the need to use the energy derived from fuel. It has an influence on the reduction of diesel consumption, eliminating fuel emission from the heating system and reduction of noise generated by a combustion device.

Figure 20 – Grayson heating device

Device parameters:

Weight 13,5kg

Electric power of the device – 10, 16 or 25 kW

Indicator of the device resistance to moisture- IP66

Four possible variants of direction of the electrical connections

Figure 21 – Side profile of Grayson heating device


Figure 22 – Heating system of bus with electric heating device

3.3 Possibility of application of the electric heating system

The concept of implementing a fully electric heating system in a bus in the passenger compartment and the driver cabin is completely different from the standard system. Using the heater and PEDRO SANZ frontbox gives such a possibility. This solution has never been used so far in the buses with a diesel engine. This is an environmental concept of a vehicle heating system, reducing the impact of the system on the exhaust emission. The electric heater is powered by additional source of electric energy with alternating current which is possible to be used in hybrid systems. The electric power of the device is 2 kW. Weight of the Pedro Sanz heater device is 2 kg. The main difference between PEDRO SANZ heater (Figure 23) and GRAYSON heating device (Figure 20) is that heater works as hot air blower while GRAYSON heating device needs an infrastructure with heat carrier (fluid) and convectors.


Figure 23 – PEDRO SANZ electric heater

The diagram proposal with PEDRO SANZ electric heater application is shown on the Figure 24


Figure 24 – Diagram of connecting the PEDRO SANZ heater

PEDRO SANZ frontbox (Figure 25) similar to the heaters is powered by an additional electric energy source, which is possible to build in a hybrid drive system. Maximum heating power is 23,3 kW and maximum cooling power is 7,1 kW (for R134a cooling factor used).

Figure 25 – PEDRO SANZ frontbox

The mechanical dimensions of PEDRO SANZ frontbox (fig.25) are: 592x240x404mm (WxHxD)


FRONTBOX E-HEATER

E-HEATER E-HEATER

E-HEATER

E-HEATER

E-HEATER

In Figure 26 a sample diagram of a heaters arrangement in a Solaris URBINO HIII 18 is presented. There a six electric heaters proposed as well as one frontbox unit for the heating system of this articulated bus.

Figure 26 – Heaters arrangement in URBINO HIII 18

The thermo heater prototype (Figure 27) developed by SPHEROS will be applied to the vehicle and tested within project task T2200.4. The efficiency of the heater which is shown on Figure 27 is up to 98% and this device has no significant impact on the installation design.

Figure 27 – Spheros thermo heater


3.4 Control of heating system components

The control of heating and air-conditioning systems takes place by means of one ATC WABCO driver, which works automatically, dismissing the driver of vehicle from the necessity of setting the device in the passenger space. The system is equipped with temperature sensors inside and outside of the vehicle, which allows building optimal comfort for passengers. The ATC driver keeps the temperature in the passenger compartment at 22 °C. There is a possibility to change service settings by +/- 2 or +/- 4 degrees. The driver controls the work of 5 heating electro valves:

1x three-way electric valve for frontbox

2x two-way electric valves for heating the passenger compartment (one per each wagon)

2x two-way electric valves for roof heating (one per each wagon) Division of work of heating in two wagons allows for better and more even/uniform steering of temperature inside the vehicle. In the driver’s cabin the driver has the possibility to set individually his working conditions like, temperature, direction and intensity of blow. ATC WABCO system has the possibility of connecting the device with software, allowing diagnosis and the introduction of parameter changes in heating and air-conditioning system. ATC WABCO driver adjustment range:

a. direction of the air flow from frontbox b. air temperature from frontbox c. intensity of the blast from frontbox d. „smog” function – internal air circulation e. on/off switch for passenger AC f. on/off switch for driver AC g. on/off switch for heating system in passenger space h. „reheat” function– drying the air inside the vehicle (evaporating of windows)

Figure 28 shows the example of water heating scheme with Cummins ISBe E4 Allison drive and air-conditioning system.


Figure 28 – Heating system with CUMMINS ISBe E4 at the rear with AC system.

3.5 Costs analysis

Costs were calculated for a prototype unit. Because of common use of listed elements the cost is exactly the same as a standard system price.


Component Supplier Prototype costs [€]

Fronbox Pedro Sanz 1096

Heater Pedro Sanz 226

Thermo Heater Spheros 1985

ENGINE

COOLER

HEATING DEVICE

ROOF HEATING ROOF HEATING

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