September 29th 2011
Text and Photographs Copyright John Gale 3rd Oct 2011
This was the first joint Symposium organised by the Lift Engineering section at the University of Northampton and the CIBSE Lift Group. The venue for this one day event was the newly opened Newton Building which is the hub of the Lift Engineering and virtual 3D NVision centre. This facility has benefited from a £11 million+ redevelopment programme which has certainly resulted in the University having a first class engineering research unit for the students and the staff alike. The whole development has been undertaken with great care and as would be expected access for the disabled has been fully catered for. The interior of the old 1915 building has been completely reconfigured and includes all the educational elements and aids required, whilst the exterior maintains the impression of a traditional university establishment. Indeed the very name Newton has been reflected in the landscaping by including a number of apple trees, under which the students can lunch and watch the fruits fall to the ground.
The event was opened by John Sinclair the University Deputy Dean and he enthusiastically introduced the delegates to the new facility which was only opened in 2010. He stressed the importance of the ‘Lift Engineering Section’ and the NVision centre and assured all of the continuing support of the University to these ‘flag ship’ specialities which were crucial to the long term plans of the University. John Sinclair expressed the desire that they would provide a front door for Graduates and Business.
Prof. Stefan Kaczmarczyk, Chair of Postgraduate Field of Lift Engineering in the School of Science and Technology, then concluded the opening address with further words of welcome and invited all attending to visit the NVision demonstration during the lunch break, gather for a group photograph after the tea break, and enjoy this Symposium on Lift and Escalator Technologies presented under the banners of the CIBSE Lifts Group and the Lift Engineering Section of the School of Science and Technology.
The morning session was divided into two halves and started with a lecture by Dr-Eur.Ing Gina Barney who presented a paper titled- Energy Models for Lifts. This was followed by three further papers, The Analysis of Excitation Sources and the Dynamic Responses in Lift Systems by Phillip Hofer (MSc. Graduate); A Reliable Forecast of Lift System Wear by Tim Ebeling; Interdependencies between the development of a Belt type Suspension and Transmission by Peter Feldhusen (MSc. Student). This concluded the first half of the morning session and a well needed coffee break was taken.
The second half of the morning session was set under way with a lecture by one of the founders of the Lift Engineering programme at the University, Phillip Andrew, who has now retired from the university but is still very active writing books and papers on Lift matters. In this lecture Mr. Andrew presented- Some thoughts on Progressive Safety Gears and Modernisation. This was followed by three more papers:- The Reliance on Testing for Modernised Lifts by Matthew Revitt (MSc. Student); A Review of the Application of Linear Motors in Vertical Transportation by Mohammadreza Nahi (MSc. Student); Is the Gearbox Dead? by Julia Munday (MSc. Graduate).
The audience and presenters were in need of sustenance at this stage and all were able to continue the dialogue over a well earned hot buffet lunch. It was during this break that the 3D visualisation suite was demonstrated and everyone was able to wear the glasses and experience a 3D tour round and through a lift system.
The afternoon session was again made up of two parts, the first of which consisted of an exciting lecture that gave an insight into multi car lift systems. This was presented by Adam Scott (Grontmij Ltd) and was titled- The Use of Multi Car/Single Well Lift Systems to Add Value. Rory Smith a well known and respected ThyssenKrupp executive followed this with his paper titled- Designing Elevator Installations Using Modern Estimates of Passenger Demand and Currently Available Elevator Technologies. The final paper of this first half of the afternoon session was- Vibrations in a Lift System by Mehdi Mottaghi (MSc. Student). This ended the first half of the afternoon session and coffee was taken or more appropriately apple juice from Newton’s apple trees.
Suitably refreshed the final session of the day started with the final invited lecture which was given by Prof. Lufti Al-Sharif. His presentations are always energetic and this one was no exception, rolling the dice and flipping the coin were just two of the activities Prof. Al-Sharif had everyone contemplating in his lecture titled The Use of Monte Carlo Simulation to Evaluate the Passenger Average Travelling Time Under Up-Peak Traffic Conditions. Two papers then followed to conclude the programme;- Development of a Control Method for Speed Pulsation in the Escalator’s Chain by Keisuke Mori (Mitsubishi Electric Corporation); Mathematical Modelling of Comparative Energy Consumption between a Single- loop Curvilinear Escalator and an Equivalent Pair of Linear Escalators by Elena Shcherbakova (City University).
Before everyone packed up and headed home, Dr. Richard Peters representing CIBSE Lift Group announced the two awards for the best student papers. The runner up was... Julia Munday who received a copy of the Andrew & Kaczmarczyk book ‘Systems Engineering of Elevators’, a hand shake and a glowing tribute from Dr. Peters. Then for the major award ... Peter Feldhusen, who received a cheque for £500 along with the ‘Systems Engineering of Elevators’ book and congratulations from the Symposium team. (photo_awards)
The following Abstracts and Summaries describe the presentations given by the invited lecturers and are précised from the book of papers. The full book of papers presented at the Symposium are available from the CIBSE Lifts Group at www.cibseliftsgroup.org at a cost of £10.00
Abstract - from the lecture given by Dr-Eur.Ing Gina Barney.
‘Energy modelling is a complex subject’. The intention of this paper is to explain some work which is being carried out at the International Standards Organisation level to suggest a simple energy reference model to support this work; and to develop a simple energy model that could be employed in a public domain traffic simulation program to predict energy consumption.
Discussion and Conclusion -
The method for taking energy measurements of an actual system using the ISO Reference Cycle will be as accurate as the instruments used and the skill of the user. The same conditions apply to the electrical current measurements made for verification. The two measurements obtained should give a good view of how well a lift is performing at the time of measurement and over time.
Prediction of the two ISO numbers is not difficult. The simple energy model proposed, based on the ISO Reference Cycle, relies on a number of simplifications. Errors in the values used will affect the shape of the power/energy profile. However, the energy used in the peaks is small compared to that used when the lift is running. As the running power is likely to be known with good accuracy, little error should occur. In any case lift suppliers usually know their product very well and will have accurate values for all these parameters.
Energy usage prediction is much more difficult. The simple model proposed can be employed to calculate energy usage. More data is required, which used to be collected when a lift was commissioned (tested/adjusted). This data enables an interpolation on a linear basis. This is not strictly correct as electric motors are magnetic devices and exhibit significant nonlinearities. Using data showing power profiles for up and down peak traffic patterns allows a reasonable attempt to predict the energy used for SPECIFIC traffic patterns. A striking feature is how little energy is used.
It is important to note that a real energy profile varies with the direction of travel and car position in the well and is not symmetrical, i.e.: exhibits nonlinearity.
The energy measurements of building services is being required more and more by various regulations, for example, in order to comply with the energy certification of buildings. Modern lifts (and some older ones too) are already very efficient, especially those based on counterbalanced systems. However, it is wise to prove this to energy inspectors and standard methods of energy measurements, conformance checking and modelling are necessary to do this.
It can be expected that third party and manufacturer modelling and simulation programs will include energy modelling as the need for it arises. It will then be possible to more accurately predict energy usage. This can be particularly useful when considering energy reduction measures.
Abstract - from the lecture given by J.P. Andrew
Where a lift has been subject to a modernisation programme, or more particularly, one or more successive cab refurbishments, resulting in a change of car mass, it is essential that the continued integrity and compliance of the safety gear be confirmed before the lift is returned to service.
In the European context, EN81-1; Annex D specifies a commissioning test with 125% rated load simply a test to ensure that the safety gear has been installed correctly and is functional. Consequently, after a modification it is not sufficient simply to perform the confirmatory test specified in Annex D.
However, there is no currently accepted method to establish free fall performance on the basis of a test with intact suspension. The objective of this paper is to discuss why that may be the case and to explore possible ways in which, whilst it may not be possible in some circumstances to establish with a reasonable degree of confidence, whether or not a given installation would have a free fall deceleration within the range required by EN81-1/EN81-2.
Point for Discussion -
It is becoming clear that North American practice is quite relaxed about the prospect that a progressive (Type B ) safety gear may have a setting which, whilst it will arrest a car in free descent, may or may not arrest a free fall. The North American view seems to be that if a performance specification similar to that required by EN81-1 were to be adopted, Typical safety gear settings would be increased, with the consequence that during ‘real time’ emergency stops, with a partial passenger load, an intact suspension and with both electromechanical brake and any dynamic braking circuit assisting with the arrest, the more severe deceleration rate is likely to result in a greater incidence of passenger injury. Given the strict inspection regimes extant in North America, the probability of a suspension failure can, to all intents and purposes be discounted, notwithstanding the catastrophic nature of the hazard. Given that higher speed lifts are, in the main, controlled by systems not linked to mains frequency, the probability of ‘uncontrolled overspeed’ of the system is much higher than that of suspension failure. It is thus considered more important to protect passengers, as far as possible from injury consequent upon severe deceleration during an arrest with intact suspension, than to guarantee arrest in free fall.
Furthermore, given our discussion of safety gear testing, after a modification, the test specified in A17/B44 (and BS2655; Part 1), allows a site test to confirm compliance, whilst acknowledging that if the stopping distance under such a test is at or near the maximum permitted, then the safety gear may not be capable of arresting the car in free fall.
Abstract - from a lecture by Rory Smith
The quantity of passengers to be transported by a lift system is a primary consideration in lift system design.
Research indicates that passenger demand in modern office buildings is significantly different to the assumptions formed many decades ago, but still applied to most modern designs.
The number and type of lifts required to provide a proper and efficient lift service may need to be revised based on these findings. These changes in lift system design have economic and environmental consequences that are favourable.
This research has indicated that in many cases it may be possible to install fewer lifts than would be indicated using the UPRTT method and still achieve excellent traffic handling.
Simulation was found to be a better method of predicting lift system traffic handling performance than the UPRTT method.
Abstract - from a lecture by Adam J Scott.
The goal of any passenger lift system design for modern buildings is to meet the required performance criteria whilst occupying the minimum amount of valuable floor space. Nowhere is this goal more relevant than in the development of major speculative office buildings where every additional square metre of space than can be made available as lettable area is a constant focus of any competent design team.
This paper focuses on the added value a multi car / single well lift system brought to the development of the St. Botolph Building, a large speculative office development in the City of London that was completed in 2010.
The St. Botolph Building is a global landmark that clearly demonstrates the real value that the adoption of an innovative multi car passenger lift system can deliver. Such a successful outcome is founded on many variables such as economic climate, developer’s appetite for risk, architectural design, etc., but for many substantial commercial developments multi car systems should be considered as a viable option to deliver.
Abstract - from the lecture given by Prof. Lufti Al-Sharif.
Monte Carlo simulation is a powerful tool used in calculating the value of a variable that is dependent on a number of random input variables. For this reason, it can be successfully used when calculating the round trip time of an elevator, where some of the inputs are random and follow pre-set probability distribution functions. The most obvious random inputs are the number of passengers boarding the car in one round trip, their origins (in the case of multiple entrances) and their destinations.
Monte Carlo simulation has been used to evaluate the elevator round trip time under up-peak traffic conditions. Its main advantage over analytical formula based methods is that it can deal with all special conditions in a building without the need for evaluating new special formulae. A combination of all the following special conditions can be dealt with: Unequal floor population, unequal floor heights, multiple entrances and top speed not attended in one floor jump. Moreover, this can be done without loss of accuracy, by setting the number of runs to the appropriate value.
This paper extends the previous work on Monte Carlo simulation in relation to two aspects; the passenger arrival process model and the passenger average travelling time.
The software is developed using MATLAB. The results for the average travelling time are compared to analytical formulae (such as that by So.et al., 2002). The results showing the effect of the Poisson arrival process on the value of the elevator round trip time are also analysed.
The advantage of the method over analytical methods is again demonstrated by showing how it can deal with the combination of all the special conditions without loss of accuracy (five conditions if the passenger arrival mode;l is added as Poisson).
The Issue of convergence, accuracy and running time are discussed in relation to the practicality of the method.
Monte Carlo simulation has been used to calculate the average passenger travelling time in an elevator system under up- peak traffic conditions. The results of the Monte Carlo simulation have been verified for the simplest cases using an analytical formula for the average travelling time that has been derived. This verification showed good agreement.
The analytical equation was further developed to deal with the case of unequal floor heights, and further verification was carried out with good agreement. The analytical equations for the average travelling time can be applied to the cases of unequal floor populations and Poisson passenger arrival model.
The strength of the Monte Carlo simulation comes to the fore when the combination of all the five special conditions exists in a building: unequal floor heights: unequal floor populations; multiple entrances; Poisson arrival model and top speed not attained. A practical design example is given to show how the method can be used to calculate the round trip time and the average travelling time.
Commentary is given on the rate of convergence of the method and the effect of the number of trials on the accuracy of the results. A guide is provided to the designer as to the trade-off between the number of trials, accuracy of the method and running time.
Closing thoughts;- The Symposium was well attended and certainly sets a blue print for future events where the organisation and hosting costs can be shared. The opportunity for experienced lecturers and Industry leaders to share the platform with students and graduates is a worthwhile objective hopefully enabling all to improve their knowledge base, communication skills and presentation presence. All those who attended certainly felt the day was time well spent and to end this report I would like to share with the readers the comments of the two key organisers:-
Professor Stefan Kaczmarczyk, Chair of the Postgraduate Field of Lift Engineering , Department of Engineering, School of Science and Technology, The University of Northampton, commented:
“Lifts and escalators are inseparable parts of office and residential buildings. They are used every day and are an absolute necessity for aged and disabled persons. However, as far as the mechanical and electrical principles of operation are concerned, people often don’t think about the mechanics of how they work, the complexities and research that go into their design and installation. Safety and reliability are key issues. The technical papers presented at this symposium reflect the latest trends and developments in these areas and gave the delegates an opportunity to discuss the current state of research and professional practice in the field of vertical transportation”
Dr Richard Peters of The CIBSE Lifts Group and Managing Director of Peters Research Ltd commented:
“The CIBSE Lifts Group are keen to support the Lift Engineering section of Northampton University. Part of that support is to help enable an accessible, peer reviewed event for the students and industry professionals to present their work. Hence this week’s joint Symposium in Northampton, which we expect will now become an annual event.”
For anyone interest in attending the 2012 Symposium the event is booked for the 27th-28th September.
JDG 3rd Oct 2011