Design and Construction of an Experimental Apparatus to Assess the Performance of a Solar Absorption Chiller with Integrated Thermal Storage

Abstract

As the prevalence of mechanical space cooling in the residential sector increases in Canada, the amount of energy consumed and greenhouse gases released is increasing.Solar absorption cooling has the potential to significantly reduce the energy consumption for space cooling. Before widespread implementation of solar cooling can be achieved throughout Canada, the feasibility and optimization of these systems must be determined for the different climatic conditions within Canada. The design and construction of a complete experimental apparatus to assess the performance of an absorption chiller with integrated thermal storage was completed. The experimental set-up consists of a controllable, variable heat source capable of supplying water at 95°C and at flow rates up to 30 L/min, a heat rejection loop, which can dissipate 30 kW of thermal energy, and a building load simulator to create realistic residential cooling profiles. In addition, a model of the experimental set-up was created in TRNSYS. This model was used to create the experimental procedure for testing the absorption chiller. Through simulation it was determined that the chiller should be run for seven complete cycles and measurements taken at 30 second time intervals. Calibration was performed on the thermocouples and thermopiles to determine a set of equations that relates the voltage produced to the temperature and temperature difference. The error on the temperature readings was determined to be ±0.49°C while the temperature difference measured by the thermopiles has an uncertainty of ±0.15°C. An uncertainty analysis was conducted on the overall experimental set-up and the uncertainty of the thermal coefficient of performance can be determined to an overall uncertainty of ±3.8 percent, while the uncertainty on the electrical coefficient of performance was found to be ±3.3 percent.ii

Evaluation of Heat Pump Water Heater Performance and Optimization Strategies In Cold Climates

“….1 has a good fit (coefficient of determination roughly equal to 1). The regression error was found to be an order of magnitude smaller than the RTD instrumentation error, and was thus determined negligible [38].…”

“…This is supported by Morrison's extensive work with solar heat pump water heater models in that time frame [18]. Further work with TRNSYS modelling of solar thermal systems has been more recently performed by Baldwin [38], Dickinson [16], and Cruickshank [39]. Although the terminal hydronic equipment varies in their cases, the solar input is of the same format.…”

“…Baldwin developed a TRNSYS model to demonstrate the efficiency of solar absorption chilling [38]. In this work, a solar thermal collector system is tied to a Climatewell absorption chiller to simulate the charging and discharging cycles.…”

“…Additional work by Baldwin included the detailed design and construction of a test apparatus for the Climatewell unit [38]. The methodology demonstrated in this work is applicable to instrumentation and hydronic related projects.…”

“…to find the total uncertainty as a collection of the uncertainty generated from each term of a characteristic equation, adapted from Figliola and Beasley[56]. the i term, known as the sensitivity factor, is found by taking the partial derivative of the characteristic equation with respect to each variable and summarizing, while the term of Equation 6.1 is the systematic error from the equipment manufacturer or other sources of standard values for natural phenomena[38].The characteristic equations chosen for the uncertainty analysis were the total net energy consumption and the COP of the HPWH, as given in Equations 5.2 and 5.3respectively. The sensitivity factors of the independent variables of Equation 5.2 were found using Equations 6.3 to 6.7.…”