Dorin Stanciu

Maximum Exergetic Efficiency Operation of a Solar Powered H2O-LiBr Absorption Cooling System

A solar driven cooling system consisting of a single effect H2O-LiBr absorbtion cooling module (ACS), a parabolic trough collector (PTC), and a storage tank (ST) module is analyzed during one full day operation. The pressurized water is used to transfer heat from PTC to ST and to feed the ACS desorber. The system is constrained to operate at the maximum ACS exergetic efficiency, under a time dependent cooling load computed on 15 July for a one storey house located near Bucharest, Romania. To set up the solar assembly, two commercial PTCs were selected, namely PT1-IST and PTC 1800 Solitem, and a single unit ST was initially considered. The mathematical model, relying on the energy balance equations, was coded under Engineering Equation Solver (EES) environment. The solar data were obtained from the Meteonorm database. The numerical simulations proved that the system cannot cover the imposed cooling load all day long, due to the large variation of water temperature inside the ST. By splitting the ST into two units, the results revealed that the PT1-IST collector only drives the ACS between 9 am and 4:30 pm, while the PTC 1800 one covers the entire cooling period (9 am–6 pm) for optimum ST capacities of 90 kg / 90 kg and 90 kg / 140 kg, respectively.

Analysis of a flat plate collector for hot water domestic use - a sensitivity study

The paper presents the study of a flat plate collector (FPC) used to heat water for domestic use in stationary operation. A comparison is provided between the cases of constant and time-dependent water circuit, in clear sky conditions. Numerical results emphasize the hot water temperature obtained with a given FPC area for a certain value of the mass flow rate. Imposing both the mass flow rate and hot water temperature, the minimum required area of the FPC can be determined. The computations are based on energy and mass balance equations. Steady state is obtained after three days of continuous operation.