2016 ASHRAE Winter Conference

While the possible impact of refrigerant leaks and subsequent dispersion in an occupied space pertains to a wide variety of applications, dynamic models that accurately describe dispersion phenomena in the built environment have not been extensively explored in the literature. This paper builds on previous work by assessing the performance of well-mixed models via a comparison to computational fluid dynamics simulations and studying the behavior of refrigerant dispersion in multiple connected spaces. Results indicate that the well-mixed models are not able to capture variation in the geometric parameters very accurately, and should be used cautiously, while the studies of the dynamics in multiple spaces highlights the importance of the location of ventilation sources and sinks.

This paper investigates the performance of liquid overfeed and DX refrigeration systems and includes components performance and system balance. This project includes the design of two refrigeration circuits, liquid overfeed flooded and DX with a common condenser, and analyzes the performance of the heat exchangers and their impact on the overall circuit’s performance. Several design techniques and methods are considered, including geometry and construction of heat exchangers. The performance of the two circuits is compared for four operating temperatures: -20°C (-4°F), -10°C (14°F), 0°C (32°F) and 5°C (4°F) and analyzed to ascertain circuits operation. DX evaporators are often utilized operating at -10°C (14°F) and below for relatively small duty systems, below 25kW (7.1 TR). However, liquid overfeed flooded evaporators’ are rarely seen practically for systems in this range. The performance of the DX and liquid overfeed flooded evaporators’ is also analyzed for small duties at the four operating conditions.

The eighty-year-old single pressure absorption refrigeration system invented by Albert Einstein and Leo Szilard is attractive as it has no mechanical moving parts and can be driven by heat alone. The literature on the refrigeration system is scarce and only theoretical analyses are available. In this paper, adversities of the primitive design and the operation of the refrigerator prototype are discussed. The prototype is able to achieve temperatures between 8°C and 14°C. Five pairs of heat inputs between 53 W and 111 W are studied. Cooling capacities decrease (from 34 W to 15 W) when the generator heat input increases, but cooling capacities increase (from 17 W to 30 W) when the bubble pump heat input increases. The highest COP is 0.25 when the heat inputs to generator is 53 W and to bubble pump is 89 W. The ideal cooling capacity and COP are 40 W and 0.28, respectively.