P. J. Diggory

Steady- and dynamic-state simulations of heat-pumps. Part II: Modelling of a motor driven water-to-water heat-pump

A mathematical model to simulate the steady- and dynamic-state behaviour of an existing water-to-water electric-motor driven heat-pump has been evolved. The condenser area on the working fluid side has been divided into two sections: namely, condensing section and sub-cooling section, while the evaporator area has been divided into an evaporating section and a superheating section. The compression has been assumed to be polytropic and the expansion isenthalpic.

Experimental studies to determine the effect of differences in absorber and condenser temperatures on the performance of a water-lithium bromide absorption cooler

Abstract Experiments have been carried out on a water-lithium bromide absorption cooler to determine the effect on performance of operating the absorber and condenser at different temperatures. The absorber temperature TAB was varied between 33.0 and 43.1°C and the condenser temperature TCO between 33.0 and 50.0°C. The experiments show that, as the temperature difference (TAB−TCO) is increased, the coefficient of performance and the cooling capacity are decreased.

Steady- and dynamic-state simulations of heat-pumps. Part I: Literature review

Various mathematical models on mechanical vapour-compression heat pumps since 1975 have been reviewed with particular emphasis on their bases and end uses. These models have been classified according to steady- and dynamicstate simulations.

Steady- and dynamic-state simulations of heat-pumps. Part III: Comparison between predictions and measurements

The mathematical models of the individual components of the heat-pump system presented in Part II have been translated into computer programs. The structures of these for steady- and dynamic-state simulation are presented. The results of the simulation have been compared with some experimentally observed data. The steady-state simulation was found to be satisfactory. Owing to the lack of data for dynamic conditions, the corresponding simulation could not be verified satisfactorily.

Experimental study of the operating characteristics of a heat pump assisted distillation system using R11 as the external working fluid

Heat pump assisted distillation with an external working fluid is one of the most obvious methods to reduce the energy consumption in a distillation process. The heat pump working fluid extracts heat from the top of the column, increases the temperature of the recovered heat and recycles it to provide the heat input to the reboiler. The interaction between the external parameters and the internal parameters for a specially designed heat pump assisted distillation system has been studied experimentally. The external parameters were mass flow rate, temperature and concentration of the feed, the concentration of the top and bottom products and the mass flow rate of the working fluid. The effects of the variations of these external parameters on the internal parameters such as the energy (steam) consumption, the actual coefficient of performance and the temperatures at the top and bottom of the column, together with the condensation and evaporation temperatures, are presented.

Capacity modulation of an experimental motor-driven heat pump

Various methods of capacity modulation of electric motor driven heat pumps have been reviewed with a particular emphasis on variable-speed motors. The effect on the steady-state performance of the heat pump, of variation in the externally-controllable independent parameters, while the compressor speed or the evaporator heat transfer area was adjusted, has been studied experimentally. Based on these results some control algorithms have been proposed.