Title of Dissertation: TRANSIENT MODELING OF TWO-STAGE AND VARIABLE REFRIGERANT FLOW VAPOR COMPRESSION SYSTEMS WITH FROSTING AND DEFROSTING Hongtao Qiao Doctor of Philosophy, 2014 Dissertation Directed By: Reinhard Radermacher, Professor Department of Mechanical Engineering This thesis presents the development of an advanced modeling framework for the transient simulation of vapor compression s...

Due to the increasing development in various branches of the automotive industry, the need for a comfort climate in the cabin is more sensible. However, to achieve climate comfort, HVAC system consumes a considerable amount of engine power. Hence, improving HVAC system performance leads to more energy saving of the vehicle which is a critical factor for nowadays automotive. Besides, one crucial...

The build-up and eruption of crystal-rich ignimbrites, commonly referred to as ‘Monotonous Intermediates’ , has been attributed to the incremental addition of new magma batches and the episodic partial melting and reactivation of rheologically locked crystal-rich magma bodies (mushes). In this study, we explore the role of volatiles exsolved from a hot intrusion underplating a crystal mush on t...

The improper defrosting operation would not only cause severe performance deterioration and energy waste but also reduce comfort. dynamic control strategy of electric vehicle heat pumps is more complicated than that other pumps. To find an efficient logic, a transcritical CO 2 pump test bench for vehicles was built. First, the thermodynamic characteristics in process were analyzed, based on whi...

Defrosting is an important issue that should be considered when air source heat pump operating in a cold climate. For the transcritical CO2 (TCHP) water heater, high pressure affects application of defrosting methods. In this paper, reverse cycle (RCD) and hot gas bypass (HGBD) methods were experimentally investigated TCHP heater. The dynamic characteristics, influences on system operation over...