14 Heat pumps

95/06449 Error rstimatlon In bin method energy calculations Hanby, V. I. Applied Energy, 1995, 52, (1). 35-45. The use of the bin method for energy calculations in heated and cooled buildings entails a compromise between the calculation time taken and the increased accuracy of using a larger numbers of bins. A deterministic expression has been developed which can be used to predict the error attributable to different degrees of discretixation. The expression was tested using two typical calculation problems, which were run using both binned input data and the parent time-series data files. The expression was found to give a satisfactory prediction of the error due to discretization.

95/06450 Hydronlc radlant cooling - Prellmlnary assessment Feustel, H. E. and Stetiu, C. Energy & Build., 1995, 22, (3), 193-205. A significant amount of the electrical ener y used to cool non-residential buildings equipped with all-air systems is % rawn by the fans that transport the cool air through the thermal distribution system. Hydronic systems reduce the amount of air transported through the b’itilding by separatmg the tasks of ventilation and thermal conditionmg.YDue to the phystcal proper- ties of water, hydronic systems can transport a given amount of thermal energy and use less than 5% of the otherwise necessary fan energy. This improvement alone significantly reduces the energy consumption and peak-power requirements of the air conditioning system. Radiant cooling has never penetrated the US markets significantly. The scope of this survey is to show the advantages of radiant cooling in combination with hydronic thermal distribution systems, as compared to the commonly-used all-air systems.

95l66461 Linear programming applied to an lndustrlal bulld- lng with several available hot refuse flows I Bojic, M. et al., Energy, Oct. 1995, 20, (IO), 1067-1074. The authors use a recovery heat exchanger (RHE) in an industrial building to heat incoming air for space heating by using the heat contents of some of the refuse hot-air flows (RAF). Several RAFs are often available with different flow rates and temperatures. A proper scenario for use of their heat contents is essential for efficient management of the energy system. Using a steady-state, bottom-up approach, they have obtained a set of equations that have linearized. Linear programming (LP) is then used and LINE software has been developed. This software has been used for an industrial building with three RAFs to obtain a use scenario corresponding to the highest energy-saving efficiency and minimum life-cycle costs of the RHE.

95/66452 Measured air-condltlonlng and thermal perform- ance of a Thal residential bulldlng Parker, D. S. Energy, Sep. 1995, 20, (9), 997-914. The author describes the measured air-con &l. * tttoning and thermal perform- ante of a typical Thai single-family residence. Although the measurements represent a single case study, it is the first time that an analysis has been performed on a Thai house with typical modem construction. In such buildings, the lack of building thermal insulation, the utilization of non- ducted au-conditioning equipment and the night-only usage patterns are quite different from conditions prevailing in Western-style buildings. Our results show that reduction to ceiling heat transfer in residential Thai build- ings is fundamental to improving cooling energy efficiency.

95166453 0 P

tlmlzatlon combined

of the speclflc rats of refrigeration In refr geratlon cycles

Chen, L. et al., Energy, Oct. 1995, 20, (lo), 1049-1053. The optimization problem of a combined refrigeration cycle formed by two endoreversible Carnot refrigeration cycles m series without intermediate reservoirs has been studied using finite-time thermodynamics. The funda- mental relation between cooling quantity and coefficient of erformance (COP) of the combined cycle is derived for a general physica Y model of a combined c cle. cific rate o ty

Relations are derived between the SROR (=optimal spe- refrigeration, i.e. the average rate of refrigeration per unit of

total heat-transfer surface area) and the COP for a piston-type, stable flow model of combined cycles. The results may be extended to an endorever- sible, combined refrigeration cycle formed by more than two endorever- sible Carnot refrigeration cycles.

95106454 An overview of chlorine-free refrigerants for centrifugal chillers Goktun, S. Energy, Sep. 1995, 20, (9) 937-940. Criteria are described for ideal working substances in centrifugal chillers. Chlorine-free fluorinated ethers and hydrocarbons are being considered as potential replacement for R-11, R-12 and R-114. Corn arisons are made in terms of ecological and thermophysical properties an x standard air-condi- tioning parameters for working substances which can be used without change of system design. R-245ca and E245fa are promising alternatives to R-11 for the low-capacity range, and R-134a is the best retrofit refrigerant for R-12 in the medium-capactty range. R-236ea, R-236ca? R-236fa, R- 236cb, and E-134 are promising refrigerants for replacmg R-114 in centrifugal chillers for the high-capacity range.

95/06455 Passlve heat transfer enhancement techniques applied to compact bubble absorber design Merrill, T. L. et al., J. of Enhanced Heat Transfer, 1995, 2. (3). 199-208. The bubb e absorbers developed for generator-absorber heat exchange abso P

aper presents performance results and analysis for three compact

?: -

tion cycles. The absorbers em K

loy passive heat transfer enhancement tee - niques, namely repeated roug ness, spiral flutes, and internal spacers. The selectton of enhancement techniques was done after a controlling heat transfer resistance analysis of a baseline absorber was completed.

95106466 nary blends

Performance of rssldsntlal rsfrlgsrators with ter-

&ri3”; M. and Tulej, P. J. Inr. J. Energy Research, Sep. 1995, 19, (7),

Comparative performance studies of ternary blends proposed as substitutes for CFC-12 are presented in this study. The experimental set-up includes a domestic refrigerator for evaluation of blend performance. Experimental data shows that the ternary blend NARM-12 consumed 35% less energy than CFC-12, and exhibits shorter cycles at comparable pressure ratios than CFC-12.

95106467 Testing and optlmlzlng the performance of a floor- based task condltlonlng system Bauman, F. S. er af., Energy & Build., 1995, 22, (3) 173-186. During recent years an increasing amount of attention has been paid to air distribution systems that individually condition the immediate environ- ments of offtce workers within their workstations. As with task lighting systems, the controls for these ‘task conditioning’ systems are partially or entirely decentralized and under the control of the occupants. Among the primary types of task conditioning systems (floor-, desktop- and partition- based), floor-based desi s are the most common, having been widely developed and used in outh Africa and Europe, and are now gaining s acceptance in the USA. The paper reports the results of recently completed laboratory measurements investigating the thermal performance of a floor- based task conditioning system.

14 HEAT PUMPS

EP” Integrated thermochemical heat-pumpknergy-

Tahat, M. A. et al., Int. J. Energy Research, Sep. 1995, 19, (7) 603-613. The feasibility of employing activated alumina and water, as reversible reaction pairs, in an integrated thermochemical heat-pump/energy-store has been studied theoretically and experimentally. The use of such a heat pum for the provision of heating and cooling applications has been investigate If . With the activated alumina absorbing water by up to 45 +/- 1% of the dry alumina’s weight, a heat of adsorption of 2.92 +/- 0.1 MJ/kg of water has been achieved.

95106459 Pool bolllng of R-11 refrigerant and water on oxl- dlzed enhanced tubes irnndIo&mu, H. E. et al., J. of Enhanced Heat Transfer, 1995, 2, (3),

- . Enhanced nucleate boiling surfaces are currently used in refrigeration and orocess heat exchanaers. Enhanced boilinn surfaces offer ootential for other applications, i&ding cooling of elec;onic equi

K ment. ?‘he possibil-

ity that the performance of such enhanced boiling su aces may be further improved by surface oxidation is addressed in this work. Ahhough the mechanism is not fully understood the current results suggest an important industrial application. The paper describes an apparatus and procedures for expanding the current limited data base for the performance of enhanced surface in pool boiling. The results of this study and the related methodol- ogy should help others address key issues of the surface geometry, oxida- tion, roughness and contact angle effects on nucleate pool boiling.

15 ENVIRONMENT

Pollution, Health Protection, Safety

95lO6460 Activated coke technology for flue gss clsanlng In waste and special waste lnclnsratlon plants Cleve, U. Brennst.-Waerme-KraF, 1994, 46, (lo), V25-37. (In German) Discusses the various cleaning technologies for flue gases from waste and special waste incinerators, including safeguards, and experiences of acti- vated coke technology. Reports on the spent activated coke disposal by desorption or combustion.

456 Fuel and Energy Abstracts November 1995