A.K. Hostrup, N. Houbak
Department of Energy Engineering, Technical University of Denmark

G.G. Maidment⁺, R.M. Tozer^*+, J.F. Missenden*
⁺School of Engineering Systems and Design, South Bank University, London,
^*Waterman Gore - Consulting Engineers, London

With recent initiatives from the UK government on reduced energy use, energy efficient systems such as CHP have been considered for new applications, including supermarkets. In these commercial buildings, the seasonal demand for heat results in underutilisation of the CHP equipment, limiting the primary energy savings that may be achieved. To increase the utilisation time, it has been proposed that heat generated by the CHP unit could be used to power an absorption refrigeration system providing cooling for the refrigerated cabinets. The application of an integrated CHP /absorption scheme or Combined Cooling Heat and Power (CCHP) in the supermarket is the subject of this paper.
The paper initially describes the cooling / heating / power requirements of a typical supermarket and then reviews a number of CCHP options involving the use of different cooling and engine technologies. The investigation calculates and compares the energy savings / capital costs of the different options against typical conventional supermarket technology.

Domingo Wilson Garagatti Arriola¹  
Silvio de Oliveira Júnior^{1,2  
(1)} Mechanical Engineering Department - Polytechnic School of the University of São Paulo, Brazil
⁽²⁾ Thermal Engineering Group - Institute for Technological Research (IPT) 05508-901, São Paulo, SP, Brazil

This paper presents the description and the exergy and thermoeconomic evaluation of a new cogeneration system, called tetra-combined cogeneration system, that generates electricity and chilled water (for air conditioning purposes) and eventually steam. This system is composed of a gas turbine, a heat recovery steam generator, a condensation/ extraction steam turbine and a hybrid absorption/steam ejection chiller.
The exergy and thermoeconomic performance (exergy based costs of electricity, steam and chilled water production) of this system is compared with the performance of a conventional cogeneration system, pointing out the advantages of this new system.

Résumé :
Cet article présente la description ainsi que l'évaluation exergétique et thermoéconomique d'un nouveau système de cogénération, appelé tetra-combiné, pour la production simultanée d'électricité, de l'eau froide et, éventuellement, de la vapeur. Le système tetra-combiné est composé par une turbine à gaz, une chaudière de récupération, une turbine à vapeur d'extraction-condensation et d'un système de réfrigération hybride absorption-ejecto-compression.
L'évaluation exergétique et thermoéconomique (évaluation des coûts de production de la vapeur, de l'eau froide et de l'électricité en base exergétique) du système tetra-combiné est comparée avec la performance d'un système conventionnel de cogénération (turbine à gaz, chaudière de récupération, turbine à vapeur d'extraction-condensation et système de réfrigération à absorption).

ENERGY RECOVERY FROM DIESEL ENGINE EXHAUST GASES FOR PERFORMANCE ENHANCEMENT AND AIR CONDITIONING

M. Talbi¹ and B. Agnew^2
1Academic of Maritime Studies, Tripoli-Libya, P. O. Box 3585
²University of Newcastle upon Tyne, department of Mechanical, Materials and Manufacturing Engineering, Newcastle upon Tyne, NE1 7RU, UK

The utilisation of exhaust waste heat is now well known and the forms the basis of many combined cooling and power installations. The exhaust gases from such installations represent a significant amount of thermal energy that traditionally has been used for combined heat and power applications. This paper explores the theoretical performance of four different configurations of a turbocharger Diesel engine and absorption refrigeration unit combination when operating in a high ambient day temperature of 35^oC. The simulation is performed using "SPICE", a well known programme commonly used for engine performance predictions. The paper examines the interfacing of the turbocharged Diesel engine with an absorption refrigeration unit and estimates the performance enhancement. The influence of the cycle configuration and performance parameters on the performance of the engine operating as a power supply with an auxiliary air conditioning plant is examined. It is demonstrated that a pre and inter cooled turbocharger engine configuration cycle offers considerable benefits in terms of SFC, efficiency and output for the Diesel cycle performance.

A.C. Oliveira¹, C. Afonso¹, J. Matos¹, S. Riffat², M. Nguyen² and P. Doherty^2
1 Faculty of Engineering, University of Porto, Rua Roberto Frias, 4200-465 Porto, Portugal
² School of the Built Environment, University of Nottingham, University Park, Nottingham, NG7 2RD, UK

A novel hybrid solar/gas system intended to provide cooling/heating and electricity generation for buildings was developed. The system is based on the combination of an ejector heat pump cycle with a Rankine cycle. It is driven by solar energy and supplemented by a gas burner. The system also uses an environmentally-friendly refrigerant to have minimal impact on the environment. Results of system computer modelling, prototype tests and economic analysis are reported. The system was judged to be viable and reliable. Technical improvements still have to be achieved to improve system economics.

M. Meckler
P.E., CPC, Director, Los Angeles Power Association; Fmr. Adjunct Professor Engineering, CSUN; President/CEO, Design Build Systems (DBS), 10573 West Pico Blvd #200, Los Angeles , CA 90064, USA

Comprehensive value engineering conducted for a Midwest (USA) developer client focused upon their architect/engineer (A/E) proposals for a nominal 100,000 sq. meter medical facility comprising under Phase 1, two 12 story medical office towers and an adjacent six (6) story hospital. Client’s A/E had originally proposed constructing separate central heating and cooling plants for each of their (i.e., originally designed) Phase I buildings. DBS Phase I BCHP plant layout and interim study results demonstrated significant building space and annual owning savings over conventionally designed individual (i.e., in-situ) building heating and cooling plant and incorporated gas and steam turbine driven chillers and integrated gas turbine driven synchronous generator resulting in an estimated 2.6 year simple payback. However, subsequent client Phase II project scope expansion undertaken prior to commencing above referenced Phase I BCHP plant construction required major design changes. The subsequent DBS Phase II redesign resulted in the elimination of higher cost temperature steam generator (HRSG) which was replaced with a low cost novel hybrid steam generator utilizing non-toxic, hot-oil energy recovery system; replacement of costly condensing steam turbine with a less expensive combination serial back pressure steam turbine and indirect single stage absorption chiller bottoming cycle; the later sized for the additional Phase II new office tower subsequently required by client all without exceeding Phase I project budgetary criteria.

J. Bassols, B. Kuckelkorn, J. Langreck, R. Schneider, H. Veelken
Colibri bv, Tentstraat 5, 6291 BC Vaals, The Netherlands

R. Tozer
Waterman Gore M&E Consulting Engineers,
Versailles Court, 3 Paris Garden, London SE1 8ND, UK
South Bank University, London, UK

The environmental impact of sorption systems is related to the way electric energy is produced in each country, and to the system configuration for which sorption systems are designed. The environmental impact of electricity production is itself a challenge, when such issues such as nuclear waste, and other contaminants are considered, in contrast to renewable fuels and hydro-electricity. In addition to this, the impact over the useful life of a sorption system needs to be considered in terms of the future trends of reducing the environmental impact of power production. These issues are discussed and proposals are made regarding life cycle environmental impact of sorption systems. In addition to this, there are different types of sorption technology (absorption, adsorption, chillers, heat pumps, heat transformers and hybrid systems), each of which has different energy ratios for cooling or heating energies, and therefore affect and impact the environment in different ways. A single-effect direct-fired chiller has a vastly different impact to an absorption heat transformer, or a CHP steam driven absorption chiller. These would be very different for countries which have predominantly nuclear, or hydroelectric or carbon fuelled electric generation. This paper addresses the theoretical and practical issues considering the market drive of existing and future technologies.