Article pulished in Applied Energy (2020)

Title: Experimental Characterization of an Innovative Hybrid Thermal-Electric Chiller for Industrial Cooling and Refrigeration Application

Language: English

Authors: Giuseppe E. Dino (*1) , Valeria Palomba (*1), Eliza Nowak (*2), Andrea Frazzica (*1).

*1: CNR ITAE, Salita S. Lucia sopra Contesse 5, 98126 Messina, Italy
*2: Fahrenheit GmbH, Siegfriedstr. 19, 80803 Munich, Germany

Abstract: The energy demand of industries accounts for about 30–35% of world yearly energy consumption, a relevant percentage is due to the need of heating and cooling demand. Solar heating and cooling technologies can be integrated in industrial processes to reduce the fossil fuels consumption as well as the related greenhouse gas emissions. This paper reports the experimental analysis of a novel hybrid sorption-compression chiller for cooling and refrigeration purposes in cascade layout, which uses silica gel/water for the sorption cycle and a low Global Warming Potential (GWP) refrigerant, i.e. propylene for the compression cycle. The experimental results highlighted the flexibility of the system in terms of performances and operating conditions, these were compared to the theoretical performances and it was found out that electricity energy savings from 15% to 25% can be achieved when using the hybrid system over a compression one with the same cooling capacity. The results were converted in performance maps and processed in a statistical model, in order to get a simplified expression for
determining the overall performances of the hybrid system through variables that could be measured by a final user, such as the operating temperatures. Optimization strategies were identified for a further enhancement of the performance of the chiller, i.e. the reduction of the electricity consumption, by controlling the intermediate temperature (evaporation temperature of the sorption chiller) through sorption cycle management and the use of variable speed of the pumps in all the circuits to reduce the parasitic consumption especially at low part loads.

Language: English

Authors: Valeria Palomba, Giuseppe E. Dino, Steffen Kühnert, Davide La Rosa, Andrea Frazzica.

Title: Experimental Evaluation of a Hybrid Adsorption-compression Cascade Chiller for Solar Cooling Applications in Industrial Processes

Language: English

Authors: Valeria Palomba, Giuseppe E. Dino, Steffen Kühnert, Davide La Rosa, Andrea Frazzica.

Abstract:

The present work reports the experimental evaluation of the performance of a cascade chiller, having an adsorption cycle as a topping cycle and a vapour compression cycle as a bottoming cycle. An experimental testing campaign was carried out at CNR ITAE, focused on the definition of performance maps of the system under different operating conditions. In particular, heat source temperatures between 70°C and 85°C were evaluated, cooling temperatures between 22°C and 40°C and chilled water temperatures of -12°C up to 5°C, in order to reproduce the operation in different seasons, climates and user requests (i.e. air conditioning and refrigeration). Cooling powers from 18 kW (under air conditioning conditions) from 12 kW (for refrigeration conditions) were obtained for the lower cooling temperatures. Indeed, the cooling temperature has a great influence on the cooling capacity of the system, whereas heat source temperature has a smaller effect on the capacity of the system. Finally, the energy savings that can arise from such a configuration were calculated and up to 25% reduction, if compared to a standard vapour compression system can be achieved. A reduction in CO2 emissions up to 3.5 yearly tons were calculated as well.

Title: Analysis of a solar hybrid cooling system for industrial applications

Language: English

Authors: Uli Jakob (*1) and Falko Kiedaisch (*1)

*1: Dr. Jakob energy research GmbH & Co. KG (JER), Pestalozzistr. 3, 71384 Weinstadt (Germany)

Abstract: This paper presents the analysis of a new Fresnel solar thermal collector (FCSP) system with a Hybrid Heat Pump (HHP) for solar cooling purposes in industry using TRNSYS simulation. The HHP is a combination of a thermally driven adsorption chiller and electric compression chiller in a cascaded configuration, to achieve highly increased Energy Efficiency Ratios (EER) for the operation of the solar assisted HHP system. The benefits of the solar assisted HHP system is mainly based on constantly low heat rejection temperature of the compression chiller, compared to conventional ambient heat rejection systems, as the adsorption chiller is responsible for the heat rejection of the entire hybrid cooling system. The evaluation of a demo case in Barcelona, Spain showed, that EERs between 7-8 can be reached, hence, the electric power consumption of the cooling system can be reduced by 29 % in transitional seasons and by 44 % during summer. As a result of this approach, it is determined that full load operation conditions of minimum 3,800 h and ambient heat rejection
conditions with above 20°C have to occur constantly through operation period, to enable an overall economic operation of the solar assisted HHP System. As an example, for the investigated industry process in Barcelona specific cooling costs of 0.031 EUR/kWh can be reached at operating hours of 4,748 h/a. Moreover, it was analysed that the solar assisted HHP system is likely feasible for the implementation into industrial process typologies with both, heat and cold demands.