PhD Thesis - Energy Systems Research Unit - University of Strathclyde

circuit were obtained and how the pressure curve coefficients (a 0 , a 1 , b 0 and b 1 ) wereeventually calibrated.Experimental data obtained from the IEA Task 38 Solar Heating and CoolingProgramme (personal communication, October 29, 2010) for the mentioned 10 kW thabsorption chiller shows that, over the working range of inlet water circuittemperatures [Lowest-Highest inlet temperature (Working Range)] specified by themanufacturer data sheet in [36] (lowest and highest hot water inlet temperature andworking range [55-95°C (40°C)], lowest and highest cooling water inlet temperatureand working range [27-35°C (7°C)] and lowest and highest chilled water inlettemperature and working range [6-20°C (14°C)], both the high pressure inside thecondenser-generator and the low pressure inside the evaporator-absorber arepredominantly effected by the hot water circuit inlet temperature, and that the inlettemperatures of the cooling and chilled water flow circuits have only a marginaleffect on the cycle pressures. Also, considering that the control scheme employed bymost chillers is to use constant water circuit flow rates and vary the hot or coolingwater inlet circuit temperature to control the output power of the absorption chiller[38], a reasonable assumption is that the cycle pressures can be expressed as afunction of hot water circuit inlet temperature. In this context, the experimental dataof Figure 3.6 shows how the high pressure inside the condenser-generator and thelow pressure inside the evaporator-absorber vary over the whole range of hot watercircuit inlet temperatures.Fig. 3.6 - Internal low and high cycle pressures vs. hot water inlet temperature118