scholarly journals Experimental Assessment of a Multi-Variable Control Strategy of a Micro-Cogeneration Solar-ORC Plant for Domestic Application

2021 ◽  
Vol 312 ◽  
pp. 08006
Author(s):  
Diego Vittorini ◽  
Fabio Fatigati ◽  
Davide Di Battista ◽  
Marco Di Bartolomeo ◽  
Roberto Carapellucci
Keyword(s):  
High Temperature ◽  
Flat Plate ◽  
Thermal Power ◽  
Energy Performance ◽  
Hot Water ◽  
Small Scale ◽  
Domestic Hot Water ◽  
Wide Range ◽  
Electrical Generation ◽  
Operating Points

Suitability to off-design operation, applicability to combined thermal and electrical generation in a wide range of low temperatures and pressures and compliance with safety and environmental limitations qualify small-scale Organic Rankine Cycle plants as a viable option for combined heat and power generation in the residential sector. As the plants scale down, the electric and thermal output maximization has to account for issues, spanning from high pump power absorption, compared to the electric output of the plant, to intrinsically low plant permeability induced by the expander, to the intermittent availability of thermal power, affected by the heat demand for domestic hot water (DHW) production. The present paper accounts for a flat-plate solar thermal collector array, bottomed by an ORC unit featuring a sliding vane expander and pump and flat-plate heat exchangers. A high-temperature buffer vessel stores artificially heated water – electric heaters, simulating the solar collector - and feeds either the hot water line for domestic use or the ORC evaporator, depending on the instantaneous demand (i.e., domestic hot water or electric power), the temperature conditions inside the tank and the stored mass availability. A low-temperature receiver acts like the heat sink of the ORC unit and harvests the residual thermal power, downstream the expander: a dedicated control, modelled to properly modulate the mass addition/subtraction to this storage unit allows to restore the operating points of the cycle and to limit the incidence of off-design operation, via real-time adjustment of the cycle operating parameters. Indeed, the possibility of continuous ORC generation depends on (i) the nature of the demand and (ii) the amount of hot water withdrawn from the high-temperature buffer vessel. The time-to-temperature for the mass stored inside the buffer affects the amount of ORC unit activations and eventually the maximum attainable generation of electric energy. The plant energy performance is experimentally assessed, and various characteristic operating points are mapped, based on test runs carried out on a real-scale ORC pilot unit.

scholarly journals Evaluation of the energy performance and cost-benefit of innovative technologies in butcher’s shops

2021 ◽  
Vol 246 ◽  
pp. 05003
Author(s):  
Jeroen Lippens ◽  
Saar Lokere ◽  
Wout Barbary ◽  
Hilde Breesch
Keyword(s):  
Energy Use ◽  
Reference Model ◽  
Cost Benefit ◽  
Energy Performance ◽  
Hot Water ◽  
Small Scale ◽  
Small Contribution ◽  
Tertiary Sector ◽  
Domestic Hot Water ◽  
Innovative Technologies

The CO2 emissions and energy use of SMEs in the tertiary sector (e.g. small food and non-food shops, restaurants, offices, pubs, etc.) are high and there are few initiatives to reduce because this target group is difficult to reach due to small scale and diversity. The Flemish-Dutch TERTS project wants (1) to make the sector aware of the potential of and (2) to demonstrate energy transition and energy efficiency of innovative technologies. This paper is focussing on butcher’s shops. A reference model is made based on data of 90 existing shops in Flanders (Belgium). The energy use of the building and systems is calculated according to DIN V 15 899. The cost-benefit of various measures is calculated and compared. Results show that the main energy consumers of a butcher shop are cooling, lighting and domestic hot water, whereas heating only has a rather small contribution. There are several cooling needs: product-cooling (in walk-in freezers, walk-in coolers and the cooling counter) and cooling of the workshop. The combination of the following measures is concluded to be the most favourable and leads to a reduction in final energy consumption of 60 %: a reflective coating on the flat roof and extra roof insulation, relighting with LED, air-to-water heat pump for the generation of domestic hot water and PV panels as local energy generation.

scholarly journals A dynamic model of an innovative high-temperature solar heating and cooling system

2016 ◽  
Vol 20 (4) ◽  
pp. 1121-1133 ◽  
Author(s):  
Annamaria Buonomano ◽  
Francesco Calise ◽  
Maria Vicidomini
Keyword(s):  
High Temperature ◽  
Simulation Model ◽  
Flat Plate ◽  
Cooling System ◽  
Energy Performance ◽  
Economic Feasibility ◽  
Solar Heating ◽  
Hot Water ◽  
Solar Collectors ◽  
Heating And Cooling

In this paper a new simulation model of a novel solar heating and cooling system based on innovative high temperature flat plate evacuated solar thermal collector is presented. The system configuration includes: flat-plate evacuated solar collectors, a double-stage LiBr-H2O absorption chiller, gas-fired auxiliary heater, a closed loop cooling tower, pumps, heat exchangers, storage tanks, valves, mixers and controllers. The novelty of this study lies in the utilization of flat-plate stationary solar collectors, manufactured by TVP Solar, rather than concentrating ones (typically adopted for driving double-stage absorption chillers). Such devices show ultra-high thermal efficiencies, even at very high (about 200?C) operating temperatures, thanks to the high vacuum insulation. Aim of the paper is to analyse the energy and economic feasibility of such novel technology, by including it in a prototypal solar heating and cooling system. For this purpose, the solar heating and cooling system design and performance were analysed by means of a purposely developed dynamic simulation model, implemented in TRNSYS. A suitable case study is also presented. Here, the simulated plant is conceived for the space heating and cooling and the domestic hot water production of a small building, whose energy needs are fulfilled through a real installation (settled also for experimental purposes) built up close to Naples (South Italy). Simulation results show that the investigated system is able to reach high thermal efficiencies and very good energy performance. Finally, the economic analysis shows results comparable to those achieved through similar renewable energy systems.

scholarly journals Multi-Variable Control and Optimization Strategy for Domestic Solar-ORC Combined Heat and Power Generation System

2020 ◽  
Vol 197 ◽  
pp. 08014
Author(s):  
Diego Vittorini ◽  
Alessio Antonini ◽  
Roberto Cipollone ◽  
Roberto Carapellucci
Keyword(s):  
Power Generation ◽  
Flat Plate ◽  
Control Strategy ◽  
Thermal Power ◽  
Energy Performance ◽  
Combined Heat And Power ◽  
Hot Water ◽  
Working Fluid ◽  
Storage Unit ◽  
Depth Analysis

The feasibility of a solar-ORC system for domestic combined heat and power generation (CHP) is deeply affected by both the time-varying ambient conditions (e.g. solar irradiance, temperature, wind speed) and the thermal and electrical load profiles variability of the final application. The definition of a proper control strategy is proven to be a major design-challenge for successful operation of solar-ORC systems, with the main goal of assuring that the thermal power demand for space heating and Domestic Hot Water (DHW) production and the electricity needs are simultaneously satisfied. The rising demand for energy-autonomous systems also calls for the inclusion of a storage system within the base-layout, that could assure the electricity demand is properly matched after sunset or in very-low irradiance conditions, such as cloudy days. A comprehensive model accounts for the dynamic of the plant-integrated unit, featuring an ORC-based plant that bottoms a flat plate solar thermal collector: a parametric study is presented, and an off-design analysis is performed to properly assess the energy performance of the system. The heat availability to the ORC heat exchanger is evaluated, based on solar availability, thermal losses in the pipes and plant requirements, in terms of operating temperature and pressures and organic fluid mass flowrate. R245fa is selected as working fluid in the ORC-section. Sliding vanes machines expander and pump – are considered as rotary equipment. Flat plate heat exchangers complete the base layout, the analysis accounts for. Due to the need for DHW production, a storage unit for hot water is present, upstream the recovery branch: dependently on the ability the fluid at the collector outlet has to meet the ORC requirements for proper operation (about 110°C), the ORC evaporator is fed and the recovery section enabled. Both continuous and unsteady operation underwent an in-depth analysis, as well as the benefits associated with different discharge times for the storage unit. A dedicated control strategy is defined, dependently on whether the electrical output or the thermal one need to be maximized, and accounts for either a flash or a progressive tank discharge. A virtual platform allowed the setting-up of a pilot plant, for direct performance assessment, in presence of different amounts of tank discharges per day and different lower temperatures at the storage tank.

scholarly journals New Deterministic Mathematical Model for Estimating the Useful Energy Output of a Medium-Sized Solar Domestic Hot Water System

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2753
Author(s):  
Miroslaw Zukowski ◽  
Walery Jezierski
Keyword(s):  
Thermal Power ◽  
Optimization Procedure ◽  
Climatic Conditions ◽  
Point Of View ◽  
Hot Water ◽  
Energy Output ◽  
Daily Consumption ◽  
Software Environment ◽  
Optical Efficiency ◽  
Domestic Hot Water

According to the authors of this paper, the mathematical point of view allows us to see what sometimes cannot be seen from the designer’s point of view. The aim of this study was to estimate the influence of the most important parameters (volume of heat storage tanks, daily consumption of domestic hot water, optical efficiency, heat loss coefficient, and total area of a solar collector) on the thermal power output of solar domestic hot water (SDHW) system in European climatic conditions. Three deterministic mathematical models of these relationships for Madrid, Budapest, and Helsinki were created. The database for the development of these models was carried out using computer simulations made in the TRNSYS software environment. The SDHW system located at the Bialystok University of Technology (Poland) was the source of the measurement results used to validate the simulation model. The mathematical optimization procedure showed that the maximum annual useful energy output that can be obtained from 1 m2 of gross collector area is 1303 kWh in the case of Madrid, 918.5 kWh for Budapest, and 768 kWh for Helsinki weather conditions.

A Design Method for Thermosyphon Solar Domestic Hot Water Systems

1987 ◽  
Vol 109 (2) ◽  
pp. 150-155 ◽  
Author(s):  
M. P. Malkin ◽  
S. A. Klein ◽  
J. A. Duffie ◽  
A. B. Copsey
Keyword(s):  
Flow Rate ◽  
Design Method ◽  
Water Systems ◽  
Hot Water ◽  
Average Flow Rate ◽  
Domestic Hot Water ◽  
Average Flow ◽  
Solar Fraction ◽  
Wide Range ◽  
Flow Circuit

A modification to the f-Chart method has been developed to predict monthly and annual performance of thermosyphon solar domestic hot water systems. Stratification in the storage tank is accounted for through use of a modified collector loss coefficient. The varying flow rate throughout the day and year in a thermosyphon system is accounted for through use of a fixed monthly “equivalent average” flow rate. The “equivalent average” flow rate is that which balances the thermosyphon buoyancy driving force with the frictional losses in the flow circuit on a monthly average basis. Comparison between the annual solar fraction predited by the modified design method and TRNSYS simulations for a wide range of thermosyphon systems shows an RMS error of 2.6 percent.

scholarly journals Analysis of energy signatures and planning of heating and domestic hot water energy use in buildings in Norway

2019 ◽  
Vol 111 ◽  
pp. 06009
Author(s):  
Tymofii Tereshchenko, ◽  
Dmytro Ivanko ◽  
Natasa Nord ◽  
Igor Sartori
Keyword(s):  
Energy Use ◽  
District Heating ◽  
Energy System ◽  
Energy Performance ◽  
Multiple Regression Model ◽  
Hot Water ◽  
Temperature Dependent ◽  
Domestic Hot Water ◽  
Dependent Part ◽  
Energy Signature

Widespread introduction of low energy buildings (LEBs), passive houses, and zero emission buildings (ZEBs) are national target in Norway. In order to achieve better energy performance in these types of buildings and successfully integrate them in energy system, reliable planning and prediction techniques for heat energy use are required. However, the issue of energy planning in LEBs currently remains challenging for district heating companies. This article proposed an improved methodology for planning and analysis of domestic hot water and heating energy use in LEBs based on energy signature method. The methodology was tested on a passive school in Oslo, Norway. In order to divide energy signature curve on temperature dependent and independent parts, it was proposed to use piecewise regression. Each of these parts were analyzed separately. The problem of dealing with outliers and selection of the factors that had impact of energy was considered. For temperature dependent part, the different methods of modelling were compared by statistical criteria. The investigation showed that linear multiple regression model resulted in better accuracy in the prediction than SVM, PLS, and LASSO models. In order to explain temperature independent part of energy signature the hourly profiles of energy use were developed.

scholarly journals Consumption and Emissions Analysis in Domestic Hot Water Hotels. Case Study: Canary Islands

2019 ◽  
Vol 11 (3) ◽  
pp. 599 ◽  
Author(s):  
Francisco Díaz Pérez ◽  
Ricardo Díaz Martín ◽  
Francisco Pérez Trujillo ◽  
Moises Díaz ◽  
Adib Mouhaffel
Keyword(s):  
High Temperature ◽  
Carbon Footprint ◽  
Canary Islands ◽  
Fossil Fuels ◽  
Heat Pumps ◽  
Hot Water ◽  
Solar Thermal ◽  
Solar Panels ◽  
Domestic Hot Water ◽  
Temperature Heat

We analyze the energy consumption of domestic hot water (DHW) in the hotels of the archipelago of the Canary Islands (Spain). Currently, systems use fossil fuels of propane and gas oil. However, this paper analyzes several alternative systems which focus on renewable and mixed energies, such as biomass, solar thermal and heat pumps systems associated with an electric generation with photovoltaic solar panels for self-consumption. The carbon footprint generated is calculated for each method of generation of DHW. In our analysis, we demonstrate that by using a high-temperature heat pump with an average coefficient of performance (COP) equal to or greater than 4.4 associated with photovoltaic solar panels, a zero-emission domestic hot water system can be achieved, when the installation area of the photovoltaic solar panels is equal to that of the solar thermal system. The importance of DHW’s carbon footprint is proven, as is the efficiency of using high-temperature heat pumps associated with photovoltaic solar panels. As such, such mixed system suggests that the generation of DHW would have zero emissions with maximum annual savings according to hotel occupancy, between 112,417 and 137,644 tons of carbon dioxide (CO2), compared to current boilers based on fossil fuels.

Comparison between Energy Performance of Building and Investments to the Renewable Energy Sources

2014 ◽  
Vol 1020 ◽  
pp. 518-523
Author(s):  
Martin Kovac ◽  
Katarina Knizova
Keyword(s):  
Renewable Energy Sources ◽  
Water System ◽  
Energy Performance ◽  
Water Systems ◽  
Hot Water ◽  
Operating Costs ◽  
Energy Sources ◽  
Domestic Hot Water ◽  
Know How ◽  
The Subject

The subject of the paper is to calculate the energy performance of building in proposed variants. The differences in the variants are in the using of conventional and renewable sources for heating and domestic hot water system. Target of the second part of paper is to know, how much money we need to invest into the proposed variants for heating and domestic hot water systems and how much money will by the user paying for operating costs. The conclusion of the paper describes the payback periods of proposed variants.

Experimental Daily Energy Performance of Flat Plate and Evacuated Tube Solar Collectors

2009 ◽  
Author(s):  
Enrico Zambolin ◽  
Davide Del Col ◽  
Andrea Padovan
Keyword(s):  
Solar Energy ◽  
Flat Plate ◽  
Energy Performance ◽  
Hot Water ◽  
Solar Collectors ◽  
Input Output ◽  
Evacuated Tube Collector ◽  
Daily Energy ◽  
Radiation Test ◽  
Evacuated Tube

New comparative tests on different types of solar collectors are presented in this paper. Tests have been performed at the solar energy conversion laboratory of the University of Padova. Two standard glazed flat plate collectors and one evacuated tube collector are installed in parallel; the evacuated collector is a direct flow through type with external CPC (compound parabolic concentrator) reflectors. The present test rig allows to make measurements on the flat plate, on the evacuated collector or on both simultaneously, by simply acting on the valves to modify the circuit. In this paper measurements of the performance of the evacuated tube collector and flat plate collectors working at the same conditions are reported. Efficiency in stationary conditions is measured following the standard EN 12975-2 [1] and it is compared with the input/output curves measured for an entire day. The main purpose of the present work is to characterize and to compare the daily energy performance of the two types of collectors. An effective mean for describing and analyzing the daily performance is the so called input/output diagram, in which the collected solar energy is plotted against the daily incident solar radiation. Test runs have been performed in several conditions to reproduce different conventional uses (hot water, space heating, solar cooling).

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