TRNSYS MODEL OF THE COMBI BOILER DOMESTIC HOT WATER CIRCUIT WITH A FOCUS ON THE PARAMETER DEFINITION OF THE PLATE HEAT EXCHANGER

Year 2023, , 191 - 205, 17.11.2023

Okan Gök , Ayşe Uğurcan Atmaca , Aytunç Erek , Hürrem Murat Altay

https://doi.org/10.47480/isibted.1391419

Cited By: 1

Abstract

Combi boilers used for both space and domestic hot water heating are one of the common household appliances. Modelling the domestic hot water circuit of a combi boiler for the preliminary evaluation of the laboratory testing is of crucial importance since it decreases the time, cost, and energy spent on the trials. There are various modelling approaches established by the authors of this paper. Domestic hot water circuit of the appliance is modelled previously making use of the Transient System Simulation Tool (TRNSYS 18) and a good agreement is achieved with the experimental and numerical data for the economic mode simulations. The drawback of the current TRNSYS model is the dependence on the experimental data for some of the parameter definitions of the components selected from the TRNSYS library, i.e. UA (multiplication of the overall heat transfer coefficient and the heat transfer area) input of the plate heat exchanger and heat retention effect of the heat cell block. In this paper, a constant value is assigned to the parameter definition of UA instead of a time dependent varied profile. Mean absolute errors covering the steady-state and transient operating regions for the domestic hot water inlet and outlet temperature difference in economic mode simulations stay nearly the same around 0,46°C, 0,82°C, and 0,53°C for 5 l/min, 7 l/min, and 8,7 l/min, respectively, under constant and variable UA approaches. Comfort operating scheme model is established with a couple of experimental data as of the principal application of the constant UA approach. Mean absolute error of the overall domestic hot water inlet and outlet temperature difference profile decreases to 0,5°C in the comfort mode simulation.

Keywords

Combi boiler, Transient system simulation, Plate heat exchanger (PHE), Domestic hot water (DHW), Comfort and economic (eco) operating modes, TRNSYS model, UA input

PLAKALI ISI EŞANJÖRÜNÜN PARAMETRE TANIMI ODAKLI KOMBİ SICAK KULLANIM SUYU HATTININ TRNSYS MODELİ

Abstract

Mahal ve sıcak kullanım suyu ısıtılması için kullanılan kombiler, yaygın olarak kullanılan ev aletlerindendir. Laboratuvar testlerinin ön değerlendirmesi için bir kombinin sıcak kullanım suyu devresinin modellenmesi, deneyler için harcanan zamanı, maliyeti ve enerjiyi azalttığı için oldukça önemlidir. Bu makalenin yazarları tarafından oluşturulan çeşitli modelleme yaklaşımları bulunmaktadır. Önceki çalışmalarda, cihazın sıcak kullanım suyu devresi Zamana Bağlı Sistem Simülasyon Aracı (TRNSYS 18) kullanılarak modellenmiştir ve ekonomik mod simülasyonları için deneysel ve sayısal veriler kullanılarak iyi bir uyum ortaya konmuştur. Mevcut TRNSYS modelinin dezavantajı, TRNSYS model kütüphanesinden seçilen bileşenlerin, plakalı ısı eşanjörünün UA (toplam ısı transfer katsayısı ve ısı transfer alanının çarpımı) girdisi ve ısı hücresi bloğunun ısı tutma etkisi gibi bazı parametre tanımlarının deneysel verilere bağımlı olmasıdır. Bu makalede, plakalı ısı eşanjörünün UA parametresi zamana bağlı değişken bir profil yerine sabit bir değer olarak tanımlanmıştır. Kombinin ekonomik çalışma modu simülasyonlarında, sıcak kullanım suyunun giriş ve çıkış sıcaklık farkı için kararlı ve kararsız süreçleri kapsayan ortalama mutlak hatalar, sabit ve değişken UA yaklaşımları altında 5 l/dk, 7 l/dk ve 8.7 l/dk için sırasıyla 0.46°C, 0.82°C ve 0.53°C olarak neredeyse sabit kalmıştır. Konfor çalışma modunun modeli, sabit UA yaklaşımının önemli bir uygulaması olarak birkaç deneysel veri ile oluşturulmuştur. Konfor modu simülasyonunda, sıcak kullanım suyu giriş ve çıkış sıcaklık farkı profilinin ortalama mutlak hatası 0.5°C'ye düşmektedir.

Keywords

Kombi, Zamana bağlı sistem simülasyonu, Plakalı ısı değiştiricisi (PID), Sıcak kullanım suyu (SKS), Konfor ve ekonomik (eco) çalışma modları, TRNSYS modeli, UA girdisi

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