HIRAC: description and transnational access
The Highly Instrumented Reactor for Atmospheric Chemistry, HIRAC, is based in the School of Chemistry at the University of Leeds, UK. HIRAC is funded by the Natural Environment Research Council, NERC, to carry out experiments which bridge the divide between the study of elementary reactions in the lab, and large scale field work. Uniquely HIRAC allows researchers the ability to simultaneously control temperature, pressure and photolysis rates during experiments. HIRAC is part of the Transnational Access of Euochamp-2.
2. Description of the research facility
HIRAC carries out a range of gas phase experiments designed to compliment the range of atmospheric chemistry related research being undertaken at the University of Leeds in the form of field, laboratory and theoretical studies. The research carried out in HIRAC covers three major obectives: i) Mechanism development linked to the Master Chemical Mechanism. ii) Field instrument development and calibration. iii) Kinetics and Structural Activity Relationship (SAR) development. More information about experiments being carried out in HIRAC can be found here.
2.1. Technical data
Detailed descriptions of HIRAC can be found here and in Glowacki et al. (ACP, 7, pp. 5371-5390, 2007). Briefly, HIRAC is a stainless steel cylinder with internal dimensions of 2.0 m long and 1.2 m diameter giving a total volume of ~2.25 m3. Due to its strong stainless steel construction experiments can be carried out over a range of pressures of any desired bath gas up to 1 atm. Partial cleaning of the chamber between experimental runs is achieved by a rotary pump backed roots blower. Thorough mixing of reaction mixtures is achieved by four low-vibration circulation fans giving mixing times of ≤ 70 s. HIRAC will undergo the installation of a temperature control system in 2010 which will enable temperature changes within the chamber from ~-70 °C to +70 °C.
Light for photochemical studies can be provided by several different types of lamps (Philips TLK40W/05 actinic UV blacklamps, GE G55T8 / OH 7G UVC lamps and Philips TL 40W/12 RS SLV UV-B medical therapy lamps) which have different spectral profiles and intensities in the UV region. The lamps are housed in eight quartz tubes mounted radially inside the reactive volume parallel to the chamber's principle axis. A combination of experimental, analytical and ray tracing results have shown that j(NO2) is within ± 15% of the average for ~75% of HIRAC's volume confirming the homogeneity of the radiation profile within the chamber.
HIRAC is fitted with a full suite of instrumentation to allow accurate and thorough characterisation of the chemistry occurring inside the chamber during experiments. Along with a number devices for measuring temperature and pressure, HIRAC is also fitted with the instruments detailed in the table below and here:
At detailed list of publications is provided here.
2.4. Access to the chamber under Eurochamp TA
Requests for access to the HIRAC chamber are processed centrally within EUROCHAMP-2 and must be made a minimum of 6 months prior to the proposed campaign. Planning of experiments and use of chamber instrumentation will be agreed prior to arrival. Typically experimental campaigns will be collaborative in nature. Experiments will have access to all equipment described in the table above for the duration of the stay. HIRAC instrumentation will be operated by Leeds personnel or training will be provided. Campaigns would be expected to last a minimum of 5 days and up to 3 weeks. This duration includes setup time and any time required to return the chamber to its original condition.
Many of the radical detection techniques are unique for a chamber of this size and HIRAC provides an ideal platform to test ideas before applying in larger outdoor chambers. The range of temperature and pressure control will be an attractive feature for those involved in mechanistic studies or interested in testing aircraft based instrumentation. HIRAC has deliberately been designed with a variety of different access ports and should be able to accommodate a variety of external apparatus for intercomparisons / calibrations or focused campaigns on a particular topic.
3. Institution in charge of the laboratory facility
The University of Leeds is one of the largest centres for atmospheric science in the UK and is recognised internationally for its excellence in atmospheric science research. The School of Chemistry was ranked 8th in the UK in the Research Assessment Exercise 2008 (RAE2008) and has an internationally leading reputation in atmospheric chemistry for field measurements of atmospheric composition, laboratory studies of chemical kinetics and photochemistry, and the development of numerical models and chemical mechanisms, including the Master Chemical Mechanism. The Atmospheric Chemistry Group consists of 5 senior experimental atmospheric chemists with a total research group size of ~30, and is closely associated with the Institute for Climate and Atmospheric Science (ICAS) in the School of Earth and Environment. Leeds also plays host to the National Centre for Atmospheric Science (NCAS) from which it receives significant support.
3.1. Contact Information
Prof. Paul Seakins, phone: +44 113 343 6568
Dr. Shona Smith, phone: +44 113 343 6550
School of Chemistry
4. Additional Information