# Investigation on the Ammonia Boiling Heat Transfer Coefficient in Plate Heat Exchangers

^{*}

## Abstract

**:**

^{2}K. Theoretical values were obtained from 12 correlations confirmed by the literature to date, developed for similar working conditions. The experimental values are close to the theoretical ones for Shah and Jokar correlations applied for a vapor quality of 0.5. The theoretical values are in the range of 1440–2076 W/m

^{2}K and 1558–2318 W/m

^{2}K, respectively. Shah correlation predicted 82.35% of all data within the ±30% error band at an MAE value of 14.23%, and Jokar et al. predicted 76.47% of all data within the ±30% error band with an MAE value of 17.7%.

## 1. Introduction

#### 1.1. General Aspects

_{2}emissions during operation).

#### 1.2. Review of Significant Research in the Field

#### 1.3. Selection of Correlations Used in the Article

Investigator | $\mathrm{Correlation}/\mathrm{Comments}$ $G\text{}[\mathrm{kg}/\text{}({\mathrm{m}}^{2}\text{}\mathrm{s}\left)\right],\text{}{q}^{\u2033}$$\text{}[\mathrm{kW}/{\mathrm{m}}^{2}],\text{}p$$\text{}\left[\mathrm{Pa}\right],$ $x[-],\text{}{p}_{r}$$\text{}\left[\mathrm{Pa}\right],\text{}{D}_{h}$ [mm] |

1. Kandlikar (1983) | ${h}_{2Ph}=\mathrm{max}\left({h}_{nb},{h}_{cb}\right)\phantom{\rule{0ex}{0ex}}{h}_{nb}=0.6683\xb7C{o}^{-0.2}\xb7{\left(1-x\right)}^{0.8}\xb7{f}_{2}\left(F{r}_{l}\right)\xb7{h}_{l}+1058\xb7B{o}^{0.7}\xb7{\left(1-x\right)}^{0.8}\xb7{F}_{Fl}\xb7{h}_{l},$ ${h}_{cb}=1.136\xb7C{o}^{-0.9}\xb7{\left(1-x\right)}^{0.8}\xb7{f}_{2}\left(F{r}_{l}\right)\xb7{h}_{l}+667.2\xb7B{o}^{0.7}\xb7{\left(1-x\right)}^{0.8}\xb7{F}_{Fl}\xb7{h}_{l},$ $Co={\left(\frac{{\rho}_{g}}{{\rho}_{l}}\right)}^{0.5}\xb7{\left(\frac{1-x}{x}\right)}^{0.8}$$;\text{}Bo=\frac{{q}^{\u2033}}{G\xb7\u2206{h}_{l-g}}$$;\text{}R{e}_{l}=\frac{G\xb7\left(1-x\right)\xb7{D}_{h}}{{\mu}_{l}}$$;\text{}f={\left[1.58\xb7ln\left(R{e}_{l}\right)-3.28\right]}^{-2}$ ${f}_{2}\left(F{r}_{l}\right)=1\text{}[-],{F}_{Fl}=1for\mathrm{stainless}\text{}\mathrm{steel}\text{}\mathrm{plate}\text{}*$ ${h}_{l}=\frac{R{e}_{l}\xb7P{r}_{l}\xb7\left(\frac{f}{2}\right)\xb7\frac{{k}_{l}}{{D}_{h}}}{1+12.7\xb7\left(P{r}_{l}^{\frac{2}{3}}-1\right)\xb7{\left(\frac{f}{2}\right)}^{0.5}}for{10}^{4}\le R{e}_{l}\le 5\xb7{10}^{6};{h}_{l}=\frac{(R{e}_{l}-1000)\xb7P{r}_{l}\xb7\left(\frac{f}{2}\right)\xb7\frac{{k}_{l}}{{D}_{h}}}{1+12.7\xb7\left(P{r}_{l}^{2/3}-1\right)\xb7{\left(\frac{f}{2}\right)}^{0.5}}$$for3000\le R{e}_{l}\le {10}^{4}$ Validity: G = 13–8179; q″ = 0.3–2280; p = 0.4–64; 30° < β < 65°, 4000 ≤ Re < 16,000; Ammonia, R22. |

2. Ayub (2003) | $h=C\xb7\left(\frac{{k}_{l}}{{D}_{h}}\right)\xb7{\left(\frac{R{e}_{l}^{2}\xb7\u2206{h}_{l-g}}{{L}_{p}}\right)}^{0.4124}\xb7{\left(\frac{{p}_{sat}}{{p}_{cr}}\right)}^{0.12}\xb7{\left(\frac{65}{\beta}\right)}^{0.35}$ C = 0.1121 for flooded and thermosyphon Validity: Ammonia, R22; 30° < β < 65°; 4000 ≤ Re < 16,000. |

3. Shah (1976, 1982) | ${h}_{2Ph}=\mathrm{max}\left({h}_{nb},{h}_{cb}\right)$ ${h}_{cb}=1.8\xb7{\left[Co\xb7{\left(0.38F{r}_{l}^{-0.3}\right)}^{n}\right]}^{-0.8}\xb7{h}_{l}$ ${h}_{nb}=F\xb7\mathrm{exp}\left\{2.74\xb7{\left[Co\xb7{\left(0.38F{r}_{l}^{-0.3}\right)}^{n}\right]}^{-0.1}\right\}\xb7{h}_{l}$ $\varphi =\{\begin{array}{c}230\xb7{\mathrm{Bo}}^{0.5}\mathrm{for}\mathrm{Bo}3\xb7{10}^{-4}\\ 1+46\xb7{\mathrm{Bo}}^{0.5}\mathrm{for}\mathrm{Bo}3\xb7{10}^{-4}\end{array};\text{}Co={\left(\frac{{\rho}_{g}}{{\rho}_{l}}\right)}^{0.5}\xb7{\left(\frac{1-x}{x}\right)}^{0.8}$$;\text{}Bo=\frac{{q}^{\u2033}}{G\xb7\u2206{h}_{l-g}}$$;F{r}_{l}=\frac{{G}^{2}}{{\rho}_{l}\xb7g\xb7{D}_{h}}$ $n=\{\begin{array}{c}0ifF{r}_{l}0.4\\ 1ifF{r}_{l}\le 0.4\end{array}F=\{\begin{array}{c}14.7\mathrm{for}\mathrm{Bo}1.1\xb7{10}^{-3}\\ 15.43\mathrm{for}\mathrm{Bo}1.1\xb7{10}^{-3}\end{array}\phantom{\rule{0ex}{0ex}}{h}_{l}=0.023\xb7\left(\frac{{k}_{l}}{{D}_{h}}\right)\xb7{\left[\frac{G\xb7\left(1-x\right)\xb7{D}_{h}}{{\mu}_{l}}\right]}^{0.8}\xb7P{r}_{l}^{0.4}$ $Validity:\text{}0.0053\le {p}_{r}\le 0.78$$;\text{}10\le G11,000$$;\text{}0.22Bo\xb7{10}^{4}74.2;0.01\le {D}_{h}\le 27.1$$;for30fluids.$ |

4. Sterner and Taborek (1992) | $h={\left[{\left({h}_{nb0}\xb7{F}_{nb}\right)}^{3}+{\left({h}_{l}\xb7{F}_{2Ph}\right)}^{3}\right]}^{1/3}$ ${h}_{l}=\frac{({\mathrm{Re}}_{l}-1000)\xb7{Pr}_{l}\xb7\left(\frac{f}{8}\right)\xb7\frac{{k}_{l}}{{D}_{h}}}{1+12.7\xb7\left({Pr}_{l}^{2/3}-1\right)\xb7{\left(\frac{f}{8}\right)}^{0.5}}$ ${F}_{nb}={F}_{pl}\xb7{\left(\frac{{q}^{\u2033}}{{{q}^{\u2033}}_{0}}\right)}^{nl}\xb7{\left(\frac{{D}_{h}}{0.01}\right)}^{-0.4}\xb7{\left(\frac{{R}_{p}}{0.000001}\right)}^{0.133}\xb7F\left(M\right)$ ${F}_{pl}=2.816\xb7{\left(\frac{{p}_{sat}}{{p}_{cr}}\right)}_{}^{0.45}+\left(3.4+\frac{1.7}{1-{\left(\frac{{p}_{sat}}{{p}_{cr}}\right)}^{7}}\right)\xb7{\left(\frac{{p}_{sat}}{{p}_{cr}}\right)}^{3.7}$ $nl=\{\begin{array}{c}0.8-0.1\xb7{e}^{1.75\xb7\left(\frac{{p}_{sat}}{{p}_{cr}}\right)}\mathrm{for}\mathrm{all}\mathrm{fluids}\mathrm{except}\mathrm{cryogenic}\mathrm{fluids}\\ 0.7-13\xb7{e}^{1.105\xb7\left(\frac{{p}_{sat}}{{p}_{cr}}\right)}\mathrm{for}\mathrm{cryogenic}\mathrm{fluids}\end{array}$ $F\left(M\right)=0.38+0.2\xb7\mathrm{ln}\left(M\right)+2.84\xb7{10}^{-5}\xb7{M}^{2}$ $\text{}$$\text{}\phantom{\rule{0ex}{0ex}}{F}_{2Ph}=\{\begin{array}{c}{\left[{\left(1-x\right)}^{1.5}+1.9\xb7{x}^{0.6}\xb7{\left(\frac{{\rho}_{l}}{{\rho}_{g}}\right)}^{0.35}\right]}^{1.1}0\le x\le 0.6\\ {\left\{{\left[{\left(1-x\right)}^{1.5}+1.9\xb7{x}^{0.6}{\left(1-x\right)}^{0.01}\xb7{\left(\frac{{\rho}_{l}}{{\rho}_{g}}\right)}^{0.35}\right]}^{-2.2}+{\left\{\left(\frac{{h}_{g0}}{{h}_{l}}\right)\xb7{x}^{0.01}\left[1+8\xb7{\left(1-x\right)}^{0.7}\xb7{\left(\frac{{\rho}_{l}}{{\rho}_{g}}\right)}^{0.67}\right]\right\}}^{-2}\right\}}^{-0.5}\\ 0.6\le x\le 1\end{array}$ $\mathit{Validity}:\text{}0.1p1100$$;\text{}0.8{q}^{\u2033}4600$$;\text{}3.9G4850$$;\text{}0.01x1.0;{{q}^{\u2033}}_{0}=150\mathit{for}\mathit{ammonia};$$\text{}{h}_{nb0}=36,640W/{m}^{2}K$for ammonia. |

5. Sterner and Sunden (2006) | $h=C\xb7\left(\frac{{k}_{l}}{{D}_{h}}\right)\xb7R{e}_{l}^{m}\xb7J{a}^{n}\xb7C{o}^{p};Ja=\frac{{\rho}_{l}\xb7{c}_{p,l}\xb7({t}_{wall}-{t}_{sat})}{{\rho}_{g}\xb7\u2206{h}_{l-g}}$$\text{};\text{}Co={\left(\frac{1-x}{x}\right)}^{0.8}\xb7{\left(\frac{{\rho}_{g}}{{\rho}_{l}}\right)}^{0.5}$ $C=18.5,\text{}m=1.05$$,\text{}n=-0.452$$,\text{}p=2.76**$ $\mathit{Validity}:\text{}Ammonia\beta =65\xb0;$ $50<R{e}_{l}<225$$;\text{}12{q}^{\u2033}185$$;\text{}0.5G0.9$$;\text{}0.05x1.0$$;-6\mathbb{C}{t}_{sat}-3\mathbb{C}$. |

6. Arima et al. (2010) | $h=16.4\xb7{h}_{l,eq}\xb7{\left(\frac{1}{{X}_{vv}}\right)}^{1.08}$$;\text{}{h}_{l,eq}=0.023\xb7\left(\frac{{k}_{l}}{{D}_{h}}\right)\xb7{\left[\frac{G\xb7\left(1-x\right)\xb7{D}_{h}}{{\mu}_{l}}\right]}^{0.8}\xb7P{r}_{l}^{0.4}$ ${X}_{vv}={\left(\frac{1-x}{x}\right)}^{0.5}\xb7{\left(\frac{{\rho}_{g}}{{\rho}_{l}}\right)}^{0.5}\xb7{\left(\frac{{\mu}_{l}}{{\mu}_{g}}\right)}^{0.5}\text{}\mathrm{laminar}-\mathrm{laminar}$ $\mathit{Validity}:\text{}\mathrm{can}\text{}\mathrm{be}\text{}\mathrm{utilized}\text{}\mathrm{for}\text{}\mathrm{evaluating}\text{}\mathrm{local}\text{}\mathrm{heat}\text{}\mathrm{transfer}\text{}\mathrm{coefficient}\text{}\mathrm{for}\text{}\mathrm{ammonia};\text{}40R{e}_{l}3600$$;\text{}15.4\le {q}^{\u2033}\le 24.5$$;\text{}7.4\le G\le 15$$;\text{}0.1\le x\le 0.9$$;\text{}0.7\le p\le 0.9$. |

7. Khan, Chyu (2010) and Khan et al. (2014) | $h=\left(-173.5\xb7\frac{\beta}{60}+257.1\right)\xb7\left(\frac{{k}_{l}}{{D}_{h}}\right)\xb7{\left(R{e}_{eq}\xb7B{o}_{eq}\right)}^{\left(-0.09\xb7\frac{\beta}{60}+0.0005\right)}\xb7{p}_{red}^{\left(0.624\xb7\frac{\beta}{60}-0.822\right)}$ ${p}_{red}=\frac{{p}_{sat}}{{p}_{cr}};\text{}R{e}_{eq}=\frac{{G}_{eq}\xb7{D}_{h}}{{\mu}_{l}}$ ${G}_{eq}=G\xb7{\left[\left(1-{x}_{m}\right)+{x}_{m}\xb7\left(\frac{{\rho}_{l}}{{\rho}_{g}}\right)\right]}^{1/2};\text{}B{o}_{eq}=\frac{{q}^{\u2033}}{{G}_{eq}\xb7\u2206{h}_{l-g}}$ $\mathit{Validity}:\text{}\mathit{Ammonia},\text{}30\xb0\beta 60\xb0$$;\text{}500R{e}_{l}2500$$;\text{}3.5P{r}_{l}6$$;\text{}1225R{e}_{eq}3000;$ $20\le {q}^{\u2033}\le 70$$;\text{}5.5G27$$;\text{}0.1x0.9$$;-2\mathbb{C}\le {t}_{sat}\le 25\mathbb{C}$. |

8. Huang et al. (2012) | $h=1.87\xb7{10}^{-3}\xb7\left(\frac{{k}_{l}}{{D}_{h}}\right)\xb7{\left(\frac{{q}^{\u2033}\xb7{d}_{0}}{{k}_{l}\xb7{T}_{sat}}\right)}^{0.56}\xb7\left(\frac{\u2206{h}_{l-g}\xb7{d}_{0}}{{a}_{l}^{2}}\right)\xb7P{r}_{l}^{0.33}$ ${a}_{l}=\frac{{k}_{l}}{{\rho}_{l}\xb7{c}_{p,l}};\text{}{d}_{0}=0.015\xb7\theta \xb7{\left[\frac{2\xb7\sigma}{g\xb7({\rho}_{l}-{\rho}_{g})}\right]}^{0.5}$$\text{}\mathrm{for}\text{}\mathrm{a}\text{}\theta \text{}\mathrm{of}\text{}35\xb0.$ $\mathit{Validity}:28\xb0\beta 60\xb0$$;\text{}1.8\le {q}^{\u2033}\le 6.9$$;\text{}5.6G52.3$$;\text{}5.9\mathbb{C}\le {t}_{sat}\le 13\mathbb{C}.$ |

9. Almalfi et al. (2015) | $h=18.495\xb7\left(\frac{{k}_{l}}{{D}_{h}}\right)\xb7{\left(\frac{\beta}{{\beta}_{max}}\right)}^{0.248}\xb7{\left(\frac{x\xb7G\xb7{D}_{h}}{{\mu}_{g}}\right)}^{0.135}\xb7{\left(\frac{G\xb7{D}_{h}}{{\mu}_{l}}\right)}^{0.351}\xb7{\left(\frac{{\rho}_{l}}{{\rho}_{g}}\right)}^{0.223}\xb7B{d}^{0.235}\xb7B{o}^{0.198};\text{}\mathrm{for}\text{}Bd\ge 4$ $Bd=\frac{\left({\rho}_{l}-{\rho}_{g}\right)\xb7g\xb7{D}_{h}^{2}}{\sigma}$$;\text{}Bo=\frac{{q}^{\u2033}}{G\xb7\u2206{h}_{l-g}}$$\text{};\text{}{\beta}_{max}=70\xb0$ Validity: These correlations are derived from a dimensional analysis, and it has a broad spectrum of applicability in the matter of refrigerant, including ammonia, and plate geometry. |

10. Danilova et al. (1981) | $N{u}_{2Ph}=3\xb7R{e}_{g}^{0.3}\xb7B{d}^{0.33}$$,\text{}0.025Re\text{}*0.25;$ $R{e}_{g}=\frac{G\xb7x\xb7{D}_{h}}{{\mu}_{g}}$$;\text{}Re\text{}*=BoR{e}_{l}=\frac{{q}^{\u2033}\xb7x\xb7{D}_{h}}{{\mu}_{l}\xb7\Delta {h}_{l-g}\xb7}$$;\text{}Bd=\frac{\left({\rho}_{l}-{\rho}_{g}\right)\xb7g\xb7{D}_{h}^{2}}{\sigma}$ Validity: As this experimental study was conducted in 1981 it includes some of the refrigerants that have been banned from the market, such as R11 or R22. However, at the same time, ammonia was one of the agents investigated during the assessment. |

11. Koyama et al. (2014) | ${h}_{l}=0.023\xb7\left(\frac{{k}_{l}}{{D}_{h}}\right)\xb7{\left[\frac{G\xb7\left(1-x\right)\xb7{D}_{h}}{{\mu}_{l}}\right]}^{0.8}\xb7P{r}_{l}^{0.4}$ $\frac{h}{{h}_{l}}=52.2\xb7{\left(\frac{1}{{X}_{vv}}\right)}^{0.9},\text{}\mathsf{\delta}=1\text{}\mathrm{mm};\text{}\frac{h}{{h}_{l}}=48.6\xb7{\left(\frac{1}{{X}_{vv}}\right)}^{0.79}$, δ = 2.5 mm Validity: According to the authors, this is applicable to ammonia boiling local and average (mean) heat transfer coefficient. |

12. Jokar et al. (2006) | $h=0.603\xb7\left(\frac{{k}_{l}}{{D}_{h}}\right)\xb7R{e}_{l}^{0.5}\xb7{p}_{red}^{0,1}\xb7{x}^{-2}\xb7{\left(\frac{{G}^{2}}{{\rho}_{l}^{2}\xb7{c}_{p,l}\xb7({t}_{wall}-{t}_{sat})}\right)}^{-0.1}\xb7{\left(\frac{{\rho}_{l}^{2}\xb7\Delta {h}_{l-g}}{{G}^{2}}\right)}^{-0.5}\xb7{\left(\frac{{\rho}_{l}\xb7\sigma}{{\mu}_{l}\xb7G}\right)}^{1.1}\xb7{\left(\frac{{\rho}_{l}}{{\rho}_{l}-{\rho}_{g}}\right)}^{2}$ ${p}_{red}=\frac{{p}_{sat}}{{p}_{cr}}$ $\mathit{Validity}:\text{}\mathrm{Flow}\text{}\mathrm{boiling}\text{}\mathrm{data},\text{}{D}_{h}$ = 4.0 mm, β = 60°. |

## 2. Materials and Methods

## 3. Results

## 4. Discussion

^{2}K. It was noticed that, when specific heat flux increases, the same trend is followed by the ammonia boiling heat transfer coefficient.

## 5. Conclusions

- −
- To date, ammonia boiling in PHE has been less approached in Romania. The experimental stand used for the present study integrates compact heat exchangers and a screw compressor. The experimental results can be considered reliable because of the high accuracy sensors used, and the values were verified by applying the energy balance both for each piece of equipment and together with the entire system.
- −
- The convection coefficient on the ammonia side in a PHE evaporator determination is a very complex process and the information available in the literature is still not extensive enough for the extended range of all the parameters involved. The contribution to the development of knowledge in the field consists of using determinations made on an experimental stand especially built for these types of investigations, using lower ammonia mass flux than in other similar studies, in the range of $1.8\u20132.6\mathrm{kg}/{\mathrm{m}}^{2}\xb7\mathrm{s}$ and a lower specific flux, having the values inside a $4\u20137.3\mathrm{kW}/{\mathrm{m}}^{2}$ interval.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## Abbreviations

Symbols | |

$A\u2014$Heat transfer area $\left[{\mathrm{m}}^{2}\right]$ | $\mathrm{M}$—Molecular mass $\left[\mathrm{kg}/\mathrm{kmol}\right]$ |

a—Thermal diffusivity $\left[{\mathrm{m}}^{2}/\mathrm{s}\right]$ | $\dot{m}$—Mass flow rate $\left[\mathrm{kg}/{\mathrm{m}}^{2}\xb7\mathrm{s}\right]$ |

$b$—Corrugation depth $\left[\mathrm{m}\right]$ | MAE—Mean absolute error [%] |

$\mathrm{Bd}$—Bond number $[-]$ | MRE—Mean relative error [%] |

$\mathrm{Bo}$—Boiling number $[-]$ | N—Number from data base |

${c}_{p}$—Specific heat $\left[\mathrm{J}/\mathrm{kgK}\right]$ | $\mathrm{Nu}$—Nusselt number $[-]$ |

$\mathrm{Co}$—Convection number $[-]$ | $p$—Pressure $\left[\mathrm{MPa}\right]$ |

$\mathrm{Dh}$—hydraulic diameter $\left[\mathrm{m}\right]$ | $\mathrm{Pr}$—Prandtl number $[-]$ |

$e\u2014$Euler number$[-]$ | P—electrical power [W] |

$f$—Darcy friction factor $[-]$ | Pc—Corrugation pitch [m] |

F—Enhancement factor for convective boiling [−] | $\dot{Q}$—Heat transfer rate [W] |

${\mathrm{F}}_{\mathrm{fl}}$—Fluid dependent factor $[-]$ | ${q}^{\u2033}$—Specific heat flux $\left[\mathrm{W}/{\mathrm{m}}^{2}\right]$ |

$g$—Gravitational acceleration $\left[\mathrm{m}/{\mathrm{s}}^{2}\right]$ | $\mathrm{Re}$—Reynolds number $[-]$ |

$\mathrm{G}$—Specific mass flux $\left[\mathrm{kg}/{\mathrm{m}}^{2}\xb7\mathrm{s}\right]$ | ${\mathrm{R}}_{p}$—Surface roughness $\left[\mathrm{m}\right]$ |

$h$—Convective heat transfer coef. $\left[\mathrm{W}/{\mathrm{m}}^{2}\mathrm{K}\right]$ | $T\u2014\mathrm{Temperature}\text{}\left[\mathrm{K}\right]$ |

$H$—Height $\left[\mathrm{m}\right]$ | U—Overall heat transfer coefficient for the plate [W/m^{2} K] |

$\Delta {h}_{l-g}$—Latent heat of vaporization $\left[\mathrm{J}/\mathrm{kg}\right]$ | $t$—Thickness $\left[\mathrm{m}\right]$ |

$\mathrm{Ja}$—Jacob number $[-]$ | ${\mathrm{X}}_{\mathrm{vv}}\u2014\mathrm{Lockhart}-\mathrm{Martinelli}\text{}\mathrm{parameter}\text{}[-]$ |

k—Thermal conductivity $\left[\mathrm{W}/\mathrm{mK}\right]$ | x—Vapor quality $[-]$ |

$L$—Length $\left[\mathrm{m}\right]$ | $W$—Width $\left[\mathrm{m}\right]$ |

Greek letters | |

$\beta $—Chevron angle $[\xb0]$ | $\mu $—Dynamic viscosity $\left[\mathrm{Pa}\xb7\mathrm{s}\right]$ |

$\epsilon $—Arithmetic mean roughness $\left[\mathsf{\mu}\mathrm{m}\right]$ | $\nu $—Cinematic viscosity $\left[{\mathrm{m}}^{2}/\mathrm{s}\right]$ |

$\varphi $—Two phase multipliers $[-]$ | $\rho $—Density $\left[\mathrm{kg}/{\mathrm{m}}^{3}\right]$ |

$\phi $—Surface enlargement factor $[-]$ | $\sigma $—Superficial tension $\left[\mathrm{J}/{\mathrm{m}}^{2}\right]$ |

λ—Statistical parameter $[-]$ | ξ—Statistical parameter $[-]$ |

Subscript | |

C—Condenser | $nb$—Nucleate boiling |

calc.—Calculated | NH3—Ammonia |

$cb$—Convective boiling | out—Outlet |

$cr\u2014$Critical | $p$—Port |

e—Evaporator | $red$—Reduced |

EG—Ethylene-glycol | $sat$—Saturation |

exp—Experimental | $sb$—Sub-critical boiling |

$g$—Vapor | $2Ph$—Biphasic |

in—Inlet | $0$—Reference value |

K—Compressor | wall—Wall |

$l\u2014$Liquid | w—Water |

$m$—Mean |

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**Figure 7.**Calculated ammonia boiling coefficients (Shah et al., Sterner and Taborek, Sterner and Sunden and Jokar et al.) related to experimental values.

Alfa Laval-Nova 76-64-H | |
---|---|

Chevron angle, β | 60° |

Corrugation depth, b | 6 mm |

Corrugation pitch, Pc | 16 mm |

Plate thickness, t | 0.4 mm |

Total plate length, L | 0.618 m |

Total plate width, W | 0.191 m |

Port length, L_{p} | 0.519 m |

Port width, W_{p} | 0.092 m |

Diameter port | 60 mm |

Plates number | 30 |

Plates number (active regarding heat transfer) | 28 |

Channels number on ammonia part | 14 |

Channels number on secondary fluid part | 15 |

Evaporator heat transfer surface, S | 6.2 m^{2} |

Surface enlargement factor, φ | 1.17 |

Hydraulic diameter Dh = 2b/φ [18] | 0.01 mm |

Plate material | AISI 316 |

Parameter | Range |
---|---|

${\dot{m}}_{NH3}$ | $0.0227\u20130.0387\text{}\mathrm{kg}/\mathrm{s}$ |

${\dot{m}}_{W+EG}$ | $1.8\u20132\text{}\mathrm{kg}/\mathrm{s}$ |

${T}_{W+EG,in}$ | $1\u20137.1\text{}\mathbb{C}$ |

${T}_{W+EG,out}$ | $-4.8\u20132.8\text{}\mathbb{C}$ |

${T}_{suction,K}$ | $1.4\u20138\mathbb{C}$ |

${T}_{sat,ammonia}$ | $-10\u2013\left(-1.5\right)\text{}\mathbb{C}$ |

${T}_{superheat,ammonia}$ | $-6.2\u20134.8\text{}\mathbb{C}$ |

${p}_{e}$_{(Absolute value)} | $3.9\u20135.1\text{}\mathrm{bar}$ |

${P}_{K}$ | $6.45\u201311\text{}\mathrm{kW}$ |

Parameter | Range |
---|---|

${\dot{Q}}_{e,exp.}$ | $21.8\u201347\text{}\mathrm{kW}$ |

${\dot{Q}}_{C,exp.}$ | $29\u201348.2\text{}\mathrm{kW}$ |

$\overline{{T}_{wall}}$ | $-6.4\u20131.7\text{}\mathbb{C}$ |

${h}_{W+EG}$ | $4437\u20136751\text{}\mathrm{W}/{\mathrm{m}}^{2}\mathrm{K}$ |

${h}_{NH3,exp.}$ | $1377\u20133050\text{}\mathrm{W}/{\mathrm{m}}^{2}\mathrm{K}$ |

Correlation | MRE | MAE | $\mathit{\lambda}\text{}\mathbf{*}$ | $\mathit{\xi}\text{}\mathbf{**}$ |
---|---|---|---|---|

Kandlikar | 42.66 | 43.89 | 23.53 | 15.69 |

Ayub | 35.15 | 37.29 | 31.37 | 17.65 |

Shah | −3.06 | 14.23 | 82.35 | 64.71 |

Sterner and Taborek | −18.26 | 21.05 | 70.59 | 43.14 |

Sterner and Sunden | −26.00 | 26.40 | 60.78 | 45.10 |

Arima et al. | 410.64 | 410.64 | 0.00 | 0.00 |

Khan et al. | 424.72 | 424.72 | 0.00 | 0.00 |

Huang et al. | 154.84 | 154.84 | 5.88 | 5.88 |

Almalfi et al. | 162.16 | 162.16 | 0.00 | 0.00 |

Danilova et al. | −83.34 | 83.34 | 0.00 | 0.00 |

Koyama et al. | 92.47 | 92.47 | 11.76 | 7.84 |

Jokar et al. | 4.51 | 17.70 | 76.47 | 62.75 |

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**MDPI and ACS Style**

Ilie, A.; Girip, A.; Calotă, R.; Călin, A.
Investigation on the Ammonia Boiling Heat Transfer Coefficient in Plate Heat Exchangers. *Energies* **2022**, *15*, 1503.
https://doi.org/10.3390/en15041503

**AMA Style**

Ilie A, Girip A, Calotă R, Călin A.
Investigation on the Ammonia Boiling Heat Transfer Coefficient in Plate Heat Exchangers. *Energies*. 2022; 15(4):1503.
https://doi.org/10.3390/en15041503

**Chicago/Turabian Style**

Ilie, Anica, Alina Girip, Răzvan Calotă, and Andreea Călin.
2022. "Investigation on the Ammonia Boiling Heat Transfer Coefficient in Plate Heat Exchangers" *Energies* 15, no. 4: 1503.
https://doi.org/10.3390/en15041503