To Investigate And Analyse And Optimize The Vapour Absorption Refrigeration System (VAR) with Vapour Compression Refrigeration System (VCR) To Improve The Efficiency And Performance Of Refrigeration Systems

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ACKNOWLEDGEMENT

I would take this opportunity to thank my research supervisor, family and friends for their support and guidance without which this research would not have been possible.

DECLARATION

I, [type your full first names and surname here], declare that the contents of this dissertation/thesis represent my own unaided work, and that the dissertation/thesis has not previously been submitted for academic examination towards any qualification. Furthermore, it represents my own opinions and not necessarily those of the University.

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ABSTRACT

The solar-thermal refrigeration systems, covering the solar absorption refrigeration system (SAbRS) and the solar adsorption refrigeration system (SAdRS), were designed for typical office in the UK. The approach of simulation-optimization was adopted in order to determine the optimal design parameters for SAbRS and SAdRS against the conventional design practice. For simulation, dynamic model of each system was refined on the TRNSYS platform. For optimization, the objective was to minimize the annual primary energy consumption of SAbRS or SAdRS in response to the changing loading and climatic conditions throughout a year. This is a constrained optimization problem since the upper limit of comfort temperature was stipulated, such that the minimization of system energy would not sacrifice the indoor thermal comfort. Due to the complex, multidimensional and constrained nature of the dynamic simulation models, the differential evolution (DE), which has been proven effective in evolutionary computation (EC), was used for optimization purpose. Through the simulation-optimization run, the optimized designs of SAbRS and SAdRS were determined, and their corresponding primary energy consumptions could be 12.2% and 7.1% less than those based on the general design practice. The results provide useful guidelines for the equipment design of SAbRS and SAdRS.

Highlights

? Solar absorption refrigeration system (SAbRS) and solar adsorption refrigeration system (SAdRS) were involved. ? Simulation-optimization was adopted to determine optimized design for SAbRS and SAdRS. ? Due to complex dynamic simulation, differential evolution (DE) was used for optimization. ? Primary energy consumptions could be 12.2% and 7.1% less for SAbRS and SAdRS respectively. ? The results provide useful guidelines for equipment design of SAbRS and SAdRS.

Keywords

Solar air-conditioning;

Absorption refrigeration;

Adsorption refrigeration;

Differential evolution;

Simulation-optimization;

Solar energy

Nomenclature

Ac: collector area (m2)

c(x): constraint violation function

Cr: crossover rate

COPm: year-round averaged coefficient of performance of chiller

Ep,para” year-round primary energy consumption of parasitic equipment (kW h)

Ep,aux: year-round primary energy consumption of auxiliary heating (kW h)

Ep,t: year-round total primary energy consumption (kW h)

F: interpolation function

f(x): objective function of optimization

G: solution function for interpolation function F

Gsolar: year-round total of solar thermal gain (kW h)

K: amplification factor

LL: lower limit of part-load control (°C)

M: mutant vector

M: component of mutant vector

mchwp: mass flow rate of chilled water pump (kg/h)

mcwp: mass flow rate of cooling water pump (kg/h)

mhwp: mass flow rate of hot water pump (kg/h)

mrwp: mass flow rate of regenerative water pump (kg/h)

msaf; mass flow rate of supply air fan (kg/h)

n: number of independent variables

Nex: number of occupied hours when the zone temperature exceeding the upper limit ...