Gregory Burgess

A Review of Ammonia-Based Thermochemical Energy Storage for Concentrating Solar Power

The development of a thermochemical energy storage system based on ammonia, for use with concentrating solar power is discussed in this paper. This is one of a number of storage options for concentrating solar power, including molten-salt storage, which is already operating commercially. The ammonia storage development has involved prototype solar receiver/reactors operated in conjunction with a 20-m 2 dish concentrator, as well as closed-loop storage demonstrations. An ongoing computational study deals with the performance of an ammonia receiver for a 489-m 2 dish concentrator. The ammonia storage system could employ industry-standard ammonia synthesis converters for superheated steam production. A standard 1500 t/day ammonia synthesis reactor would suffice for a 10-MWe baseload plant with 330 large 489-m2 dishes. At this stage, an updated economic assessment of the system would be valuable.

COMPARISON OF SUBJECTIVE AND OBJECTIVE MEASURES OF MOVEMENT PERFORMANCE OF CHILDREN WITH CEREBRAL PALSY

The outcome of an eight‐week period of additional occupational therapy, aimed at improving fine motor skills, was assessed by accelerometry and a rating scale based on the Erhardt Developmental Prehension Assessment. 10 children with cerebral palsy received their regular occupational therapy, while a similar group had an additional 30‐minute session each day. No difference was found between groups at the end of the study. The difficulties of designing this type of project are discussed and the assessment methods described.

Photogrammetric monitoring of the construction of a solar energy dish concentrator

Close-range photogrammetry has been used to control the construction of a jig used in the assembly of a new generation solar concentrator and the validation of the final, mirrored surface. The concentrator is a concave paraboloid dish with an area of a 489 m(2). The typical photogrammetric relative precision realized was 1:175,000, corresponding to an accuracy of better than 1 mm at the jig reference points. The validation of the mirrored surface achieved a relative precision of 1:300,000. Photogrammetry was also used to characterize the dish mirror panels. The rear surface of the panels was mapped, as it made possible a denser target array and quicker image capture than if the reflective surface was used. The targets were produced with a digital projector, and the typical measurement precision attained was 1:150,000. This paper describes the equipment and techniques required to provide the required accuracy and precision for the jig and panel surfaces.

An Experimental Study of Ammonia Receiver Geometries for Dish Concentrators

This paper presents experimental evaluation of ammonia receiver geometries with a 9 m 2 dish concentrator. The experiments involved varying the geometric arrangement of reactor tubes in a thermochemical reactor built from a series of tubes arranged in a conical shape inside a cavity receiver. Differences in conical arrangement were found to affect the efficiency of energy conversion. The solar-to-chemical efficiency gain obtained by varying the receiver geometry was up to 7% absolute. From this, it is apparent that geometric optimizations are worth pursuing since the resulting efficiency gains are achieved with no increase in costs of manufacture for receivers. The experimental results and methodology can be used when developing receivers for larger dish concentrators, such as the second generation 500 m 2 dish concentrator developed at the Australian National University.

Heat flux and temperature measurement technologies for concentrating solar power

Abstract: Heat flux and temperature are two fundamental quantities to be determined in the design of solar receivers for concentrating solar power (CSP) plants. Heat flux measurement allows the determination of the efficiency of solar receivers; a range of radiometers and calorimeters have been developed for this purpose. To provide accurate spatial resolution, the camera target approach has been widely applied by concentrating solar thermal (CST) RD contact thermometry of solar irradiated material surfaces has limitations at very high temperatures, and infrared measurement is the most reliable alternative. However, reflected solar radiation can be an important source of error in this non-contact methodology. This chapter presents some of the most modern systems to measure both heat flux and temperature.

Novel Parabolic Trough Collectors Driving a Small-Scale Organic Rankine Cycle System

This paper presents component performance results of a new parabolic trough collector array driving an organic Rankine cycle (ORC) power generation system. The system has been installed in the National Solar Energy Centre at CSIRO Energy Technology in Newcastle, NSW, Australia. It consists of four rows of 18 parabolic mirrors each in a 2×2 matrix with a total aperture area of approximately 132m2 . The absorber tube is a laterally aligned, 40mm copper tube coated with a semi-selective paint and enclosed in a 50mm non-evacuated glass tube to reduce convection losses. The mirror modules, which are light-weight and robust, are made from thin low iron back silvered glass bonded to a sheet steel substrate. They are supported by a box truss on semi circular hoops running on rollers for single axis tracking. The mirror design has been chosen to allow low-cost manufacturing as well as simple commissioning and operation. The ORC unit is a FP6 unit sourced from Freepower Ltd. with a net power output of 6kWel at 180°C inlet temperature and a total heat input of 70 kWth . It uses a two-stage expansion process with hydrofluoroether as the working fluid. A wet cooling tower is used to dissipate the reject heat from the ORC. The two key components of the envisioned system are the trough reflector/receiver and the ORC unit. The optical performance of the mirror elements was investigated with regard to the flux mapping onto the receiver tube. The ORC unit has been tested separately using an electrical oil heater as the heat source. This paper presents results for irradiation capture and intensity over the receiver width of a single trough mirror module. The complete system including trough collectors and ORC has not been in transient operation yet, thus experimental steady-state results of the ORC unit are presented.© 2007 ASME