Comparison of the working domains of some compression heat pumps and a compression-absorption heat pump

Technical and economic working domains of industrial heat pumps: Part 2 – Ammonia-water hybrid absorption-compression heat pumps

“…The reduction of vapour pressure allows the design of high temperature heat pumps with standard pressure refrigeration components, (Brunin et al, 1997;Jensen et al, 2014). While the non-isothermal phase change allows the temperature profiles of the absorber and desorber to match those of the external circuits, thereby attaining a reduction of the entropy generation caused by heat transfer over a finite temperature difference.…”

“…These installations have a heat load ranging from 150 kW to 1200 kW and a heat supply temperature up to 85 ○ C (Hybrid Energy AS, 2015). Brunin et al (1997) evaluates the working domain of the HACHP based on one technical constraint: maximum pressure and two physical parameters applied as economic indicators: minimum coefficient of performance (COP) and minimum volumetric heat capacity (ratio between heat output and compressor displacement volume). The working domain by Brunin et al (1997) is evaluated at a fixed 10 K temperature difference, between inlet and outlet, for both the heat sink and heat source.…”

“…Brunin et al (1997) evaluates the working domain of the HACHP based on one technical constraint: maximum pressure and two physical parameters applied as economic indicators: minimum coefficient of performance (COP) and minimum volumetric heat capacity (ratio between heat output and compressor displacement volume). The working domain by Brunin et al (1997) is evaluated at a fixed 10 K temperature difference, between inlet and outlet, for both the heat sink and heat source. Under these constraints, Brunin et al (1997) shows that In recent years the maximum pressure for standard refrigeration components have reached 28 bar and further high pressure components have entered the market for R717, allowing a maximum pressure of up to 50 bar, at the time of writing.…”

“…The working domain by Brunin et al (1997) is evaluated at a fixed 10 K temperature difference, between inlet and outlet, for both the heat sink and heat source. Under these constraints, Brunin et al (1997) shows that In recent years the maximum pressure for standard refrigeration components have reached 28 bar and further high pressure components have entered the market for R717, allowing a maximum pressure of up to 50 bar, at the time of writing. It is thus relevant to investigate whether the increase in attainable pressures allows higher heat supply temperatures to be reached.…”

“…Further, Brunin et al (1997) does not include the compressor discharge temperature as a constraint but, as discussed in Jensen et al (2014) the compressor discharge temperature is a limiting factor for the development of a high temperature HACHP.…”