The following is a list of research areas that the Thermodynamics and Kinetics Laboratory has pursued in the past or is currently pursuing.
 
 

1) Confined Fluids

a) Thermal Sciences: Liquid-vapour phase transitions
 

Coordinated, steady state evaporation and condensation experiments have been conducted with water under conditions where no buoyancy-driven convection was present. The temperature in the liquid phase during the condensation experiments was inverted compared to that during evaporation. Independently of the direction of molecular transport at the interface, the measured interfacial vapour temperature was greater than that in the liquid, and the temperature profile measured in the liquid phase near the interface (~0.3 mm) during both evaporation and condensation was uniform, indicating the presence of mixing or equilibration processes in the liquid phase near the interface. Statistical rate theory (SRT) indicates that the direction of the net molecular transport is that in which the entropy change resulting from a molecule going from one phase to another is positive, and when the conditions at the interface predicted from this theoretical approach are compared with those measured, close agreement is found. Physically, the results indicate that the higher energy molecules escape the liquid phase during evaporation, and the lower energy molecules of the vapour are captured by the liquid during condensation. For both phase change processes then, the molecular energy distribution in a liquid layer near the interface is disturbed. The measured uniform temperature profile in this layer may result from the equilibration processes occurring there.

b) Surface Sciences: Effect of adsorption on wetting phenomena

In a recent Space Shuttle experiment, water partially filling a closed, glass cylinder was observed to adopt a contact angle near 30°. In a ground-based laboratory, a common observation is that in a glass capillary, water has a contact angle near 0°. The reason for the special wetting properties of water during the Space Shuttle experiment are being investigated. The present indication is that they result from the configuration adopted by water in a glass cylinder when on the orbiting Space Shuttle. In the adopted configuration, the pressure is very near the saturation vapour pressure corresponding to the temperature. As a result, there is very strong adsorption at the solid-vapour interface. This adsorption reduces the surface tension of the solid-vapour interface, causing the contact angle to increase.
 

Fuel cell devices involve a number of molecular, atomic and electronic transport processes, as well as surface reactions. Some of the transport processes occur in bulk fluid and solid phases, but others involve molecular transport across the interface between bulk phases. In the design of these devices, one of the important issues is the identification of the rate-limiting process. The sequence of processes leading from gas-phase hydrogen at the anode and the gas-phase oxygen at the cathode to water production by a fuel cell that is operating in steady state is being studied with statistical rate theory (SRT).

3) Biomedical Engineering
 

The mechanism by which the protein channels of biological membranes are opened is being studied using a new theory of kinetics (Statistical Rate Theory - SRT). The mechanism involves the adsorption (binding) of Ca ions to the proteins of biological membranes (gating currents) and the subsequent generation of an electric potential difference across the interfaces of the membranes. Under voltage clamp conditions, the gating currents as a function of time can be predicted with SRT.