Direct introduction internal evaporation liquid nitrogen engine

Rizvi, Syed Farukh Javaid (2019). Direct introduction internal evaporation liquid nitrogen engine. University of Birmingham. Ph.D.

Rizvi2019PhD.pdf
Text - Accepted Version
Restricted to Repository staff only until 2 August 2050.
Available under License All rights reserved.
Download (4MB)

Abstract

The preservation of a cleaner environment is a very well-known challenge of this era. Our high dependency on fossil fuels and the by-products of their combustion is hazardous to human health and environment. Until now due to lower CO2 emissions diesel fuel was considered to be more environmentally friendly as compared to other fossil fuels. The more detailed quantification of the health hazards related to Particulate Matter and Nitric Oxides emissions from the combustion of diesel and other fossil fuels has triggered research for alternative energy sources. As a result, in this thesis research was conducted and presented on the use of Liquid Nitrogen (LN2) in an engine for power generation and vehicle propulsion in addition to the potential for utilising the available cold in air-conditioning and food preservation.

This study is focused only on the engine power output of directly introduced LN2 and the analysis of related aspects (inlet, outlet and in-cylinder pressure, temperature, conditions for LN2 evaporation etc.) that indicate the possible viability for the development of Direct Introduction Internal Evaporation (DI-IE) LN2 Engine. Earlier published research work on cryogenic engines, such as the Dearman Engine relied mostly on the pre-evaporated LN2 in the heat exchanger. The behaviour of Cryogenic Liquid Nitrogen (LN2) Direct Induction (not injection) into a four-stroke internal evaporation (IE) engine was evaluated with the help of theoretical thermodynamics calculations. Comprehensive thermodynamics calculations showed that there is enough enthalpy in the air-LN2 mixture of a DI-IE LN2 engine, enabling introduced LN2 to be fully evaporated and expanded, leading to power generation. This hypothesis was further verified by CFD simulations by two different platforms AVL Boost and ANSYS Fluent. In addition, the simulation data provided more information with regard to the features of the DI-IE LN2 engine. The evaporation of LN2 in the presence of hot air, as a result of the compression stroke and with the addition of water (as heat exchange fluid) injection, was also studied with the help of ANSYS dynamic simulation software. It has provided the opportunity to visualise the changes in temperature and pressure inside the cylinder at different crank angles with the help of animation and colour coded pictures. There was enough pressure created inside the cylinder and the temperature remained positive in the cylinder at all times. LN2 injection mass flow rate was synchronised with air intake to evaluate the optimum combination.

Given a positive outcome of theoretical calculations and simulation results, it was decided to evaluate it with experiments. A small scale prototype experimental engine was designed and manufactured to evaluate the theoretical and simulation data. Experiments were carried out, with atmospheric pressure and the introduction of pressurised LN2 up to 15 bar. Successful running of the engine validated the theoretical calculations and simulation results. In-cylinder conditions mainly the enthalpy of the air was greater than the injected amount of LN2 in each cycle, generating the in-cylinder pressure for the power stroke due to the expansion of LN2. An insulated and enhanced valve mechanism can enhance the operability and performance of the current cryogenic engine. Simulations results, including IMEP, effective torque, and power, were compared with similarly sized diesel and gasoline engines at low speeds. An effective power of 1 kW was produced with an LN2 engine of 773 cm3 size at 500 rpm with further increased to 1.43 kW at 1000 rpm. The consumption of LN2 in the investigated engine was much lower than the earlier researched engines, with external evaporation of the LN2.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):