Project Summary
This project aims to develop, optimize, and manufacture A Combined Water Production/Dew Point Cooling Unit for Low Carbon Vehicles.
This project will couple a combined water production/dew-point evaporative cooling (WP/DPEC) unit with a vapour compression system to produce a Mobile Air Conditioning (MAC) system that is more energy efficient than a compression unit alone. The dew-point evaporative cooler (DPEC) will be compact in order to be suitable for installation on vehicles, so has a flat-plate structure with a number of mini channels, with walls made from a superior heat/moisture transfer material, such as cellulose fibre, the channels include two generic types: wet and dry, and the wet and dry channels are arranged alternately.
Vaporisation of water in the wetted channel causes the temperature of the walls to be lower, hence cool the air in the adjoining channels. Theoretically, the temperature of the wetted wall is equal to the wet-bulb temperature (also adiabatic saturation temperature) of the air flowing through the wetted channel. When air is cooled, its wet-bulb temperature is also reduced and eventually towards its dew-point.
At the outlet of the dry channel the air has been cooled to have its wet-bulb temperature close to its dew-point, and therefore the temperature of the wetted wall near the inlet of the wet channel could be close to the dew-point of the air at point 1. Usually, the air coming out of the dry channel is split into two streams (channels 1 and 3) one as the product air and other as the process air for the following humidification, but the ratio between two air streams is difficult to control. In contrast, the University of Nottingham (UoN) has proposed that the process air and the product air initially go through different channels to overcome the difficulty in controlling the split ratio.
Work Packages
12 Month Project
Overall project to be led by AVID Technology Group Ltd with tasks spread amongst 6 work packages over 1 years.
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1 - 36 Months WP1:
System specifications
A further literature review will be carried out to classify the specifications of different vehicle air conditioning (MAC) systems in terms of capacity, operation characteristics, configuration and climate condition.
This will help to identify how a DPEC can be incorporated with a MAC system and its potential contribution to reducing the cooling load of a MAC system.
A preliminary system specification for the target vehicle type will be produced.
Visit to or communication with relevant manufacturers will be made in order to establish a focus group. The project brief including objectives, plan and potential outcome will be distributed to them to attract their interest and get their involvement.
A focus group meeting is expected to get their advice about the proposed technology and system specifications.
WP1 will be led by the project leader AVID with the close support from the project partners and the academic partner UoN. -
Months WP2:
Computer simulation and optimisation
The mathematical model for each component of the proposed hybrid WP/DPEC/CO2-MAC system will be given to form the basis for a computer simulation programme in Matlab or EES. The computer model will be used to predict the potential contribution by DPEC to improve the performance of CO2-MAC and the required capacity of desiccant water production.
The simulation will be first carried out for the UK climate condition to predict the potential annual energy saving by the proposed technology, assuming various MAC usage schedules. The simulation will be then extended to cover different typical climate conditions worldwide to indicate the potential energy saving for some selected locations.
The simulation results will be used to optimise the size of DPEC considering energy saving, additional weight and space allowed on various vehicles. A mapping between the vehicle type, MAC capacity and climate conditions is expected to be produced. In addition, AVID will also use their in-house software to simulate the mechanical performance of DPEC.WP2 will be led by UoN because they have expertise in computer modelling of miscellaneous air conditioning systems. The outcome of WP1 will be referred to.
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Months WP3:
Design, construction and testing of a prototype
Based on the outcomes of WP1 and WP2, a prototype WP/DPEC with a cooling capacity of around 3kW and a water production capacity of 3kg/hour will be designed and constructured. The laboratory testing of the prototype WP/DPEC will be conducted in an environmental chamber with the controlled temperature and humidity to determine the performace of WP/DPEC under the simulated different climate conditions.
The protoype WP/DPEC will be connected to a CO2-MAC system which may have a cooling capacity of around 3kW- 5kW. The CO2-MAC system will be constructed using commercial components and be suitable to replace the similar capacity R134a system on a minibus or car. The hybrid WP/DPEC/CO2-MAC sysytem will be also tested in the above environment chamber to investigate its operating characterists with various control modes. The data will be compared with the simulation results to tune the computer models for futher optimisation study.
WP3 will be led by EPS Ltd who will design and construct the desiccant rotor and the CO2-MAC system, taking into consideration the suitability of system for installation of on a chosen minibus or car. EPS, PAK and AVID will manufacture the prototype DPEC, while UoN will provide the design of DPEC and carry out the laboratory testing. The focus group will be consulted about the suitability of the prototype for installation on a vehicle. -
Months WP4:
Risk management, trials and monitoring, and commissioning
The proposed technology will be evaluated against existing and emerging international standards. A risk assessment of installation and operation of the system will be conducted for a selected vehicle type. The input or feedback from the focus group will be crucial for this assessment. The laboratory testing results and experience will be referred to in the assessment. The potential risk and mitigation measures will be identified.
Following the successful risk management, the prototype WP/DPEC/CO2-MAC system will be installed for trial under mobile conditions. The system performance will be monitored by recording temperatures, pressures, flow rates, on-off cycle period and rotational speed of the compressor. The monitoring is expected to be carried out for a number of selected days over at least 3 months. -
Months WP5:
Economic and environmental assessment
On the basis of WP1~4 outcomes, detailed economic and environmental assessments of the proposed technology will be carried out and health and safety issues will be further investigated.
The specifications of the proposed technology in relation to the capital cost, running cost, payback period and market acceptance will be evaluated for different vehicle types. The potential reduction in CO2 emissions will be predicted for various scenarios.
WP5 will be led by AVID and EPS Ltd with a support from UoN considering their experience in sustainability evaluation. -
Months WP6:
Dissemination and exploitation
Dissemination of the project outcomes will be carried out through workshops/seminars/conferences, articles in professional/technical journals, an open day and exhibitions. A dedicated website providing information on the project will also be established. The prototype system installed on a used car will be demonstrated to visitors and manufacturers, particularly to the focus group, in order to attract wider interest for exploitation of the proposed technology.
Although the project industrial partners automatically forms a supply chain, it is expected to expand this supply chain as the outcome of dissemination activities to link design, manufacture, supply and end-use by involving more OEMs of vehicles.
WP6 will be led by the project leader AVID with support from all project partners.
Project Market
Low Carbon Energy
The principal business opportunity for the consortium is provided by the UK manufacturer of the combined water production/dew point coolingdew-point evaporative cooling unit (WP/DPEC) for installation both in UK-manufactured vehicles and for export. This is exactly the specialised area of the project leader, AVID, and the project partners, PAK Ltd, and EPS. The consortium recognises that local manufacture in other territories may be more appropriate in some instances than export from the UK, so anticipates also licensing this technology to vehicle air conditioning (MAC) system manufacturers worldwide.
The project leader AVID is a Tier 1 supplier of electrified ancillary systems and thermal management systems to global heavy duty and high performance vehicle OEM’s It is focused on innovative automotive engineering design, particularly on development of components for low carbon vehicles. Use of low energy MAC is one of key considerations in their design practice. The energy consumption from the MAC system is recognised as beign a key design challenge on vehicles, in particular battery electric vehicles where energy consumed by the MAC directly reduces driving range of the vehicle. In addition thermal management of advanced high energy density battery systems also requires a sub-cooling system which is essentially a second MAC system that is utilised to manage the temperature of the battery pack.
The business opportunity has been created primarily by the EU regulation to outlaw R134a from MAC systems manufactured in the EU, and also by demand for low energy air conditioning for low carbon vehicles for both the cabin and also for the battery pack. Even vehicles intended for export are forbidden from using R134a so the EU decision has global implications, especially since the same vehicle may be used in both inside and outside to the EU.
The vehicle industry wants an MAC technology that is both energy efficient and does not contain flammable refrigerants. The WP/DPEC / CO2-MAC will simultaneously meet regulatory and industry requirements and is thus an attractive business opportunity. Applying a new design to a vehicle is always a challenge at the initial stage. This is actually one of the main objectives of this proposed project, to address the packaging problem by developing a compact WP/DPEC unit and identifying the suitable way to integrate it with the existing MAC system. The objective of this project is to develop and demonstrate an ultra low energy MAC system suitable for cabin and powertrain thermal management based on the WP/DPEC cycle
