Shiming Xu

Bio: Shiming Xu is an academic researcher from Dalian University of Technology. The author has contributed to research in topics: Bubble & Heat transfer coefficient. The author has an hindex of 9, co-authored 17 publications receiving 197 citations.

State of the art on the flammability of hydrofluoroolefin (HFO) refrigerants

Abstract: Hydrofluoroolefins (HFOs) have been attracting increasing attention over the recent decade, and some of them are regarded as candidates for next-generation refrigerants. In this paper, the flammability characteristics of forty-eight HFOs and blends have been relatively comprehensively and systematically summarized, for a variety of experimental conditions on the basis of the results reported in academic journal papers, professional books, conference proceedings, technical reports, patent applications, material safety data sheets, and presentations. The following flammability characteristics of HFOs are reviewed, including the lower flammability limit, upper flammability limit, burning velocity, minimum ignition energy, hot surface ignition temperature, autoignition temperature, thermal decomposition temperature, heat of combustion, product of combustion, etc. Besides, a new correlation equation has been suggested to roughly indicate the burning velocity and heat of combustion rankings of the fluorinated hydrocarbons once their basic molecular characteristics are known. In addition, the experimental methods, influencing factors, inerting mechanism, and developing tendency of the flammability of the HFO refrigerants are discussed. The details presented are expected to be useful for researchers working in the field of heating, ventilation, and air conditioning and refrigeration.

Development of bubble absorption refrigeration technology: A review

Abstract: This study reviews the developments of bubble absorption refrigeration technologies. Firstly, the principles of the bubble absorption refrigeration systems as well as bubble absorbers were introduced; And then bubble behavior characteristics during the absorption process were observed and expressed graphically; Thirdly, available bubble absorbers were investigated, modeled and compared; In addition, current and potential refrigerant-absorbent pairs in the bubble absorption refrigeration systems were analyzed, and about fifty fluids were involved totally. What’s more, methods of enhancing bubble absorption performance were researched, and also the influence mechanisms of these physical and chemical methods were explained; Finally, the development of bubble absorption refrigeration technologies were discussed from the aspects of driving energies, performance enhancement and application extension. The tendency of bubble absorption refrigeration technologies is expected to be high efficiency, miniaturization, and intellectualization. The expressed contents in this paper are expected to be useful for readers in the fields of absorption refrigeration technologies and the medium-low grade heat utilization technologies, especially for the equipment operating in the unsteady conditions (e.g. swing, bump, jolt, scram, etc.).

Numerical simulation of an advanced energy storage system using H2O–LiBr as working fluid, Part 1: System design and modeling

Abstract: The advanced energy storage technology proposed and patented by authors can be applied for cooling, heating, dehumidifying, combined cooling and heating, and so on. It is also called the variable mass energy transformation and storage (VMETS) technology in which the masses in one or two storage tanks change continuously during the energy charging and discharging processes. This paper presents an advanced energy storage system using aqueous lithium bromide (H2O–LiBr) as working fluid. As one of VMETS systems, this system is a closed system using two storage tanks. It is used to shift electrical load and store energy for cooling, heating or combined cooling and heating. It is environmental friendly because the water is used as refrigerant in the system. Its working principle and process of energy transformation and storage are totally different from those of the traditional thermal energy storage (TES) systems. The electric energy in off-peak time is mostly transformed into the chemical potential of the working fluid and stored in the system firstly. And then the potential is transformed into cold or heat energy by absorption refrigeration or heat pump mode when the consumers need the cold or heat energy. The key to the system is to regulate the chemical potential by controlling the absorbent (LiBr) mass fraction or concentration in the working fluid with respect to time. As a result, by using a solution storage tank and a water storage tank, the energy transformation and storage can be carried out at the desirable time to shift electric load efficiently. Since the concentration of the working solution in the VMETS cycle varies continuously, the working process of the VMETS system is dynamic. As the first part of our study, the working principle and flow of the VMETS system were introduced first, and then the system dynamic models were developed. To investigate the system characteristics and performances under full-storage and partial-storage strategies, the numerical simulation will be performed in the subsequent paper. The simulation results will be very helpful for guiding the actual system and device design.

Electrical Conductivity of Lithium Chloride, LithiumBromide, and Lithium Iodide Electrolytes in Methanol, Water, and TheirBinary Mixtures

Abstract: Low-grade thermal energy can be converted to electricity by integrating multi-effect distillation and reverse electrodialysis technologies. The energy conversion efficiency of such a system is stro...

HFO refrigerants: A review of present status and future prospects.

Abstract: HFCs (Hydrofluorocarbons) are one of the most widely used refrigerants worldwide. But, HFCs are heading towards complete phase out in the near future due to environmental concerns. A high global warming potential (GWP) of HFCs is the main reason for its phase-out. As a result, researchers, engineers and technicians associated with the refrigeration sector are looking for a suitable environment-friendly alternative. Recent past has witnessed the emergence of a new group of environment-friendly refrigerants known as the HFOs (Hydrofluoro-olefins). The present review is focussed on addressing various aspects of HFO refrigerants such as the thermodynamic and transport properties, flammability and oil compatibility, boiling and condensation heat transfer performance and their performance in actual vapour compression refrigeration systems. Few suggestions for future research work related to HFO refrigerants are also discussed.