Discal attachments of the human temporomandibular joint

The document attached has been archived with permission from the Australian Dental Association (8th Jan 2007). An external link to the publisher’s copy is included.Background: Despite its clinical significance, the anatomy of the human temporomandibular joint (TMJ) and its relationship to the lateral pterygoid muscle remains poorly described and often misrepresented in standard texts. The aim of this study was to describe how the anterior and posterior attachments of the TMJ disc vary between lateral, central and medial regions of the joint. Methods: Ten left TMJs were removed en bloc from cadavers and serial sections were made at 3-4mm intervals. Observations were made to ascertain the anterior and posterior attachments of the disc and the joint structures were traced from standardized photographs. Results: Laterally, the capsule and lateral discal ligament merged prior to their attachment at the condylar pole. Medially, muscle fibres, capsule and the disc converged on the medial pole of the condyle. There was no evidence that fibres of the upper head of the lateral pterygoid muscle inserted directly into the disc. The upper head inserted into the condyle either directly at the pterygoid fovea or via a central tendon or indirectly via the capsule. Posteriorly, the superior part of the posterior attachment of the disc attached to the cartilaginous meatus and tympanic part of the temporal bone. The inferior part of the posterior attachment of the disc attached to the posterior surface of the condyle. In four joints, this attachment was folded beneath the posterior band of the disc, creating a wedge-shaped flap that ran medio-laterally. Conclusion: This study is in broad agreement with other anatomical TMJ studies but there are two main points of difference. Firstly, a true muscle insertion of the superior head of the lateral pterygoid muscle to the disc was not observed. Secondly, a wedge-shaped flap of retrodiscal tissue was identified between the condyle and the disc.JE Christo, S Bennett, TM Wilkinson and GC Townsen

Discharge performance of blended salt in matrix materials for low enthalpy thermochemical storage

A novel study is undertaken on low cost thermochemical storage which utilizes temperatures which are compatible with low grade renewable energy capture. The discharge performance of thermochemical storage matrix materials is assessed using a custom developed experimental apparatus which provides a means of comparing materials under scaled reactor conditions. The basic performance of three salts (CaCl2, LiNO3 and MgSO4) was investigated and their subsequent performance using layering and blending techniques established that the performance could be increased by up to 24% through the correct choice of mixing technique. Layering the CaCl2 on the LiNO3 provided the most efficient thermal release strategy and yielded a thermal storage density of 0.2 GJ/m3. The research also uniquely highlights the important finding that incorrect mixing of the materials can lead to a significant reduction in efficiency with freely mixed CaCl2 and LiNO3 possessing a storage capacity of less than 0.01 GJ/m3 as a result of chemical interactions between the deliquesced materials in close proximity. The paper has impact for the design and control of thermochemical storage systems as it clearly identifies how performance can be improved or degraded by the choice and the structuring of the materials

Investigation of a household-scale open sorption energy storage system based on the Zeolite 13X/water reacting pair

Sorption thermal energy storage is a promising concept for seasonal heat storage. Advantages of sorption heat storage are high energy storage density (compared to sensible and phase change heat storage) and negligible energy losses during storage over long time periods. In order to investigate the potential of sorption thermal energy storage, a high power open sorption heat storage system has been designed and built for household space heating applications. In this paper, the characteristics of the open zeolite 13X/water sorption energy storage system will be presented. The setup consists of four segments with a total capacity of 250 L of zeolite. A segmented reactor has been designed to reduce the pressure drop over the system, which results in less required fan power. This configuration also decreases the response time and makes the system scalable. Dehydration of the reactor is performed by supplying hot air to the zeolite bed. Hydration is performed by supplying humidified air to the bed. In all the segments, the pressure drop, temperature, and humidity are monitored. Furthermore, inside one of the reactor segments, the temperature is monitored at different locations in the zeolite bed. Several tests, using different mass flow rates, have been performed. During the tests, a maximum temperature step of 24 °C was realized. The maximum delivered power was 4.4 kW and the obtained storage capacity was 52 kWh. The reactor efficiency was 76% taking into consideration the conductive heat losses through the reactor wall and the sensible heat taken up by the thermal mass of the solids. Furthermore, it has been noticed that the flow through the bed was not completely uniform. This has a negative influence on the performance of the system

Hot tap water production by a 4 kW sorption segmented reactor in household scale for seasonal heat storage

Replacing fossil fuel by solar energy as a promising sustainable energy source, is of high interest, for both electricity and heat generation. However, to reach high solar thermal fractions and to overcome the mismatch between supply and demand of solar heat, long term heat storage is necessary. A promising method for long term heat storage is to use thermochemical materials, TCMs. The reversible adsorption–desorption reactions, which are exothermic in the hydration direction and endothermic in the reverse dehydration direction, can be used to store heat. A 250 L setup based on a gas–solid reaction between water–zeolite 13X is designed and tested. Humid air is introduced into a packed bed reactor filled with dehydrated material, and due to the adsorption of water vapour on TCM, heat is released. The reactor consists of four segments of 62.5 L each, which can be operated in different modes. The temperature is measured at several locations to gain insight into the effect of segmentation. Experiments are performeignore.txtd for hydration–dehydration cycles in different modes. Using the temperatures measured at different locations in the system, a complete thermal picture of the system is calculated, including thermal powers of the segments. A maximum power of around 4 kW is obtained by running the segments in parallel mode. Compactness and robustness are two important factors for the successful introduction of heat storage systems in the built environment, and both can be met by reactor segmentation. With the segmented reactor concept, a high flexibility can be achieved in the performance of a heat storage system, while still being compact. The system is also able to produce domestic hot tap water with the required temperature of 60 °C. This can be done by implementing a recuperating unit to preheat the inflow by recovering the residual heat in the outflow. In this work, the recuperator is simulated by a heater, and applicability of the system for domestic purposes is assessed. An energy density of 198 kWh/m3 is calculated on material level, and the energy density calculated on reactor level is around 108 kWh/m3 and 61 kWh/m3 for experiment without and with preheating, respectively

Using representative time slices for optimization of thermal energy storage systems in low-temperature district heating systems

\u3cp\u3e 4 \u3csup\u3eth\u3c/sup\u3e generation district heating and cooling networks (shortly THERNETs) are often coined as a crucial technology to enable the transition towards low-carbon smart energy systems. Most importantly, they open perspectives for integration of low-grade residual heat from industry, renewable energy sources (such as geothermal heat and cold and solar thermal collectors), more efficient energy conversion units (such as collective heat pumps), while thermal energy storage (TES) systems increase system flexibility. In order to optimize design and control of such complex systems, a toolbox modesto (Multi-objective district energy systems toolbox for optimization) is under development. However, the representation of seasonal heat and cold storage systems on an annual basis requires large computational power. In an attempt to decrease computational cost, a technique with representative time slices (inspired by and combining aspects from optimization studies of electrical energy systems, unit commitment problems, thermal systems with short term energy storage and smaller scale industrial thermal systems with longer term energy storage) is developed and tested. The aim of this study is to investigate the applicability of such representative time periods to optimize seasonal TES systems in THERNETs. To this end a full year optimization is compared to one with representative time periods for a realistic case study that uses demand profiles from the city of Genk (Belgium) and energy system parameters from Marstal (Denmark). This comparative study shows that modelling with representative periods is sufficient to mimic the behaviour of a full year optimization. However, when curtailment of solar heat injection occurs, not all representations yield the same results. It was found that for the studied case, a selection of 12 representative weeks performs best, while all reduced optimizations result in a substantial reduction (speed-up of on average x4.8 to x7.7) of the calculation time. \u3c/p\u3